diff --git a/ALGORITHMS.md b/ALGORITHMS.md
index 3a3dabf..627a4c2 100644
--- a/ALGORITHMS.md
+++ b/ALGORITHMS.md
@@ -183,14 +183,18 @@ The center is the average of the points, weighted by their separation (as Box3D:
 twice). µ is the static friction when the center slides slower than 1 cm/s, the dynamic friction otherwise.
 
 ### Restitution
-Applied once after the substeps, for the contacts hitting faster than 1 m/s. The bounce impulse goes towards the
-velocity `-e * vn_before` (Newton), and is at most `e` times the impulse which stopped the point, its normal impulse of
-the step (Poisson's hypothesis, W. J. Stronge, Impact Mechanics):
+Applied once after the substeps, for the contacts hitting faster than 1 m/s, once their compression is over (the
+point doesn't approach anymore). The bounce impulse goes towards the velocity `-e * vn_impact` (Newton), and is at most
+`e` times the impulse of the compression (Poisson's hypothesis, W. J. Stronge, Impact Mechanics):
 ````
-λ = max(0, min(-m (vn + e * vn_before), e * λ_step))
+λ = max(0, min(-m (vn + e * vn_impact), e * λ_compression))
 ````
+An impact starting at the very end of a step is compressed over 2 steps: the point keeps its approach velocity and its
+compression impulse (`ImpactVelocity`, `CompressionImpulse`, warm started like the impulses) and bounces at the end of
+the second step, with the whole impulse. Bounced at the end of the first step, a ball dropped from 1 m at 60 Hz gave
+back 10 % of its height instead of 92 % (`TestBounceRestitution`, at every rate).
 Both are needed: a pile of balls bouncing with `e = 1` gains energy with Newton alone (411 J) or Poisson alone
-(3523 J), not with both (`TestRestitutionNeverAddsEnergy`). The bounce uses the velocity before the step: a body not
+(3523 J), not with both (`TestRestitutionNeverAddsEnergy`). The bounce uses the approach velocity of the impact: a body not
 round and spinning fast can turn its point away before the end of the step, and bounce higher than it fell over
 `e = 0.5` (see ARCHITECTURE.md, as documented by Jolt). Newton's law is the one of the game engines (Box2D, Jolt).
 
diff --git a/ARCHITECTURE.md b/ARCHITECTURE.md
index 6637859..0a7419f 100644
--- a/ARCHITECTURE.md
+++ b/ARCHITECTURE.md
@@ -113,9 +113,9 @@ restitution, continuous collision, islands), without allocation.
   of contact never stops (no sleep).
 - A capsule resting across a bump of a terrain can stay a few mm in the terrain: the contact of a triangle comes from
   the feature of the body above the triangle, the middle of the capsule is missed.
-- The restitution is applied once per step, with the velocity before the step: a body not round (box, capsule),
-  bouncy (`e` over 0.5) and spinning fast (20-50 rad/s) can bounce higher than it fell. Measured: up to +60 % of
-  energy at `e = 1`, never up to `e = 0.5`. Jolt documents the same limit.
+- The restitution is applied once per step, with the approach velocity of the impact: a body not round (box,
+  capsule), bouncy (`e` over 0.5) and spinning fast (10-20 rad/s) can bounce higher than it fell. Measured at 60 Hz
+  with 8 substeps: up to +21 % of energy at `e = 1`, never up to `e = 0.5`. Jolt documents the same limit.
 - No kinematic bodies (moving platforms): a body is static or dynamic.
 - The continuous collision stops the fast bodies against the static bodies (and the bullets against all the bodies),
   not the other pairs: 2 fast dynamic bodies rely on their speculative contacts (2 cm) and on the spring of the contact.
diff --git a/PHYSICS_GUIDE.md b/PHYSICS_GUIDE.md
index f6013f8..6760c60 100644
--- a/PHYSICS_GUIDE.md
+++ b/PHYSICS_GUIDE.md
@@ -128,7 +128,7 @@ are twice as stiff.
 - Higher values = less overlap under load (stacks), but it is capped at 1/8 of the substeps rate: `substeps / dt / 8`.
 - Lower values = softer contacts.
 
-With 12 substeps at 50 Hz, a stack of 10 boxes of 50 cm sinks by ~23 mm (Box2D v3.1: 30 mm): a contact sinks by
+With 8 substeps at 60 Hz, a stack of 10 boxes of 50 cm sinks by ~32 mm (Box2D v3.1: 30 mm): a contact sinks by
 (load / mass) g / (2π hertz)² under its load. A stiffer world sinks less, but a heavy body landing on a light one bounces
 more.
 
@@ -138,7 +138,7 @@ travel during the step. Between 2 dynamic bodies, from 2 cm only: a fast body ca
 spring of the contact pushes it out.
 A fast body is also moved back to its first impact with a static body (continuous collision). Set `IsBullet` on a small
 fast body (a projectile) to stop it on the dynamic bodies too.
-A ball at 40 m/s does not go through a 4 cm wall at 50 Hz.
+A ball at 40 m/s does not go through a 4 cm wall at 60 Hz (nor at 80 m/s).
 
 ### Sleep
 The bodies touching each other form an island. An island resting for 0.5 s (all its bodies under 0.05 m/s and 0.05 rad/s)
diff --git a/README.md b/README.md
index 57d4179..edcbd48 100644
--- a/README.md
+++ b/README.md
@@ -74,18 +74,20 @@ end
 - The bodies touching each other sleep and wake up together (islands).
 
 ### Why not XPBD anymore
-Up to v0.2.0, Feather used a simplified XPBD solver. The same scenes (`bench/`, 50 Hz, 12 substeps):
+Up to v0.2.0, Feather used a simplified XPBD solver. The same scenes (`bench/`), each version at its own setting:
+TGS Soft at 60 Hz with 8 substeps (the setting of Feather for the games), v0.2.0 at 50 Hz with 12 substeps (the
+setting AkmonEngine ran it with; v0.2.0 has no default):
 
 | Scene | v0.2.0 (XPBD) | TGS Soft | Expected |
 |---|---|---|---|
-| Pyramid of 55 boxes, 3 s | explodes (top box at 134 m) | stands (4.748 m) | 4.750 m |
+| Pyramid of 55 boxes, 3 s | explodes (top box at 93 m) | stands (4.744 m) | 4.750 m |
 | Box on a 20° slope, µ = 0.6 | slides 9.9 m | 0 m | 0 m |
-| Box on a 35° slope, µ = 0.3 | slides 16.9 m | 9.654 m | 9.648 m |
-| Bounce from 1 m, restitution 0.5 | 0.06 m | 0.24 m | 0.25 m |
+| Box on a 35° slope, µ = 0.3 | slides 16.9 m | 9.657 m | 9.648 m |
+| Bounce from 1 m, restitution 0.5 | 0.06 m | 0.23 m | 0.25 m |
 | 10 N during 1 s on 32.7 kg | 15279 m/s | 0.306 m/s | 0.306 m/s |
-| Same scene, run twice | 39/40 bodies differ | identical | identical |
+| Same scene, run twice | 38/40 bodies differ | identical | identical |
 | EPA sphere-box normal (p99) | 2.7° | 0.03° | 0° |
-| Step, 10 / 100 / 500 bodies resting on the ground (one layer of boxes & spheres), 1 worker | 0.41 / 1.94 / 8.8 ms | 0.03 / 0.27 / 1.28 ms | |
+| Step, 10 / 100 / 500 bodies resting on the ground (one layer of boxes & spheres), 1 worker | 0.39 / 1.82 / 8.3 ms | 0.017 / 0.11 / 0.57 ms | |
 
 ```
 cd bench
@@ -93,8 +95,8 @@ go run .                                            # current version
 go run -tags v020 -modfile=go.v020.mod .            # v0.2.0
 ```
 
-Both versions run 12 substeps at 50 Hz. A heavier scene, 500 boxes & spheres falling on each other (`BenchmarkWorldStep`),
-takes ~5.5 ms per step on 1 worker, ~1.9 ms on 8 workers.
+A heavier scene, 500 boxes & spheres falling on each other (`BenchmarkWorldStep`, 60 Hz, 8 substeps), takes ~2.1 ms
+per step on 1 worker, ~0.8 ms on 8 workers; 2000 bodies awake, 6.5 ms and 2 ms.
 
 ### Constraints
 - Contact: generated when a collision is detected between two rigid bodies, up to 4 points (manifold), with friction,
diff --git a/bench/baseline.json b/bench/baseline.json
index 6ad530e..a66d839 100644
--- a/bench/baseline.json
+++ b/bench/baseline.json
@@ -3,240 +3,240 @@
   "machine": "AMD Ryzen 7 5800X 8-Core Processor, 16 CPUs",
   "scenes": {
     "joint chain": {
-      "fingerprint": "d1a5ea3300908477",
+      "fingerprint": "bbc058aa78169d6b",
       "quality": {
         "energy gain": {
           "value": 0,
           "unit": "%"
         },
         "worst stretch": {
-          "value": 14.543678411172328,
+          "value": 23.533696297483242,
           "unit": "mm"
         }
       },
-      "stepMs": 0.328752724,
+      "stepMs": 0.22311584999999998,
       "phasesMs": {
-        "broad phase": 0.020677631999999998,
-        "continuous": 0.0071531039999999995,
-        "islands": 0.00039,
-        "narrow phase": 0.002524448,
-        "prepare": 0.007260608,
-        "restitution": 0.002520576,
-        "substeps": 0.288045396
+        "broad phase": 0.017644506666666667,
+        "continuous": 0.00651629,
+        "islands": 0.0003651733333333333,
+        "narrow phase": 0.001953446666666667,
+        "prepare": 0.006912803333333333,
+        "restitution": 0.0024563633333333336,
+        "substeps": 0.18710773
       }
     },
     "pile of 500": {
-      "fingerprint": "d77ecceae0f7eea3",
+      "fingerprint": "89a8e3b082e60588",
       "quality": {
         "landing depth": {
-          "value": 0.6667135029494731,
+          "value": 0.7094191378169967,
           "unit": "mm"
         }
       },
-      "stepMs": 0.8717517,
+      "stepMs": 0.6791402333333334,
       "phasesMs": {
-        "broad phase": 0.10925642666666666,
-        "continuous": 0.006046853333333333,
-        "islands": 0.0031442933333333334,
-        "narrow phase": 0.19552514666666668,
-        "prepare": 0.06466241333333334,
-        "restitution": 0.022133499999999997,
-        "substeps": 0.4699285266666666
+        "broad phase": 0.08666362222222222,
+        "continuous": 0.005989455555555555,
+        "islands": 0.002344294444444444,
+        "narrow phase": 0.1715676777777778,
+        "prepare": 0.06523973333333334,
+        "restitution": 0.022554666666666667,
+        "substeps": 0.3238681666666667
       }
     },
     "pyramid": {
-      "fingerprint": "8e5af8ae9965f091",
+      "fingerprint": "54ab4d46f955f41a",
       "quality": {
         "worst drift": {
-          "value": 15.06227698815896,
+          "value": 15.192243559737292,
           "unit": "mm"
         }
       },
-      "stepMs": 0.07744509399999999,
+      "stepMs": 0.06185963,
       "phasesMs": {
-        "broad phase": 0.004263816,
-        "continuous": 0.000223382,
-        "islands": 0.000181226,
-        "narrow phase": 0.01077844,
-        "prepare": 0.005719314,
-        "restitution": 0.001080206,
-        "substeps": 0.05503125
+        "broad phase": 0.004302788333333333,
+        "continuous": 0.000238935,
+        "islands": 0.00017517166666666668,
+        "narrow phase": 0.010100315,
+        "prepare": 0.005921648333333334,
+        "restitution": 0.0010952066666666668,
+        "substeps": 0.039858965
       }
     },
     "rain on terrain": {
-      "fingerprint": "1b2a75beae934de5",
+      "fingerprint": "ce4a4303727cef5d",
       "quality": {
         "fell through": {
           "value": 0,
           "unit": ""
         },
         "landing depth": {
-          "value": 9.743546541685353,
+          "value": 13.293387340110788,
           "unit": "mm"
         }
       },
-      "stepMs": 11.176997512,
+      "stepMs": 8.771267506666666,
       "phasesMs": {
-        "broad phase": 0.11957176800000001,
-        "continuous": 4.397838452,
-        "islands": 0.0061450639999999996,
-        "narrow phase": 3.8915379320000003,
-        "prepare": 0.314780984,
-        "restitution": 0.046029851999999996,
-        "substeps": 2.398003156
+        "broad phase": 0.11279914666666668,
+        "continuous": 3.3886523299999998,
+        "islands": 0.006130206666666666,
+        "narrow phase": 3.35082459,
+        "prepare": 0.29880713,
+        "restitution": 0.04598874,
+        "substeps": 1.5650291333333333
       }
     },
     "slope pile": {
-      "fingerprint": "e807a7a4a0748f09",
+      "fingerprint": "75bf00ecbdccec15",
       "quality": {
         "landing depth": {
-          "value": 1.517463711187439,
+          "value": 1.9723109923968085,
           "unit": "mm"
         },
         "resting depth": {
-          "value": 0.22507290545181746,
+          "value": 0.13806021507134503,
           "unit": "mm"
         }
       },
-      "stepMs": 0.7030997449999999,
+      "stepMs": 0.5377869291666666,
       "phasesMs": {
-        "broad phase": 0.084426155,
-        "continuous": 0.030294555,
-        "islands": 0.00084816,
-        "narrow phase": 0.07793892,
-        "prepare": 0.03624791,
-        "restitution": 0.010420575000000001,
-        "substeps": 0.46253020999999994
+        "broad phase": 0.07539907916666667,
+        "continuous": 0.0285632375,
+        "islands": 0.0009086416666666666,
+        "narrow phase": 0.07304387083333334,
+        "prepare": 0.036801824999999996,
+        "restitution": 0.0106496,
+        "substeps": 0.31201233749999996
       }
     },
     "solver2d ball and chain": {
-      "fingerprint": "5495df4bcca4c3ab",
+      "fingerprint": "c8a1bfe7890359b0",
       "quality": {
         "finite": {
           "value": 1,
           "unit": ""
         },
         "worst gap": {
-          "value": 0.5545802126429944,
+          "value": 0.5372876825478579,
           "unit": "mm"
         }
       },
-      "stepMs": 0.332302912,
+      "stepMs": 0.3265644366666667,
       "phasesMs": {
-        "broad phase": 0.022754055999999998,
-        "continuous": 0.00524216,
-        "islands": 0.000386164,
-        "narrow phase": 0.001125564,
-        "prepare": 0.008728556,
-        "restitution": 0.00268974,
-        "substeps": 0.291197784
+        "broad phase": 0.020490386666666666,
+        "continuous": 0.004699053333333333,
+        "islands": 0.00037907333333333333,
+        "narrow phase": 0.0009667766666666667,
+        "prepare": 0.008522596666666667,
+        "restitution": 0.0026978566666666665,
+        "substeps": 0.28863832333333334
       }
     },
     "solver2d bridge": {
-      "fingerprint": "dd9b5224748922e2",
+      "fingerprint": "a3db5d8b1a677b65",
       "quality": {
         "finite": {
           "value": 1,
           "unit": ""
         },
         "sag": {
-          "value": 0.25237870005618745,
+          "value": 0.25784495328753465,
           "unit": "m"
         },
         "worst gap": {
-          "value": 0.23602681912618909,
+          "value": 0.2313907905724356,
           "unit": "mm"
         }
       },
-      "stepMs": 0.5801432160000001,
+      "stepMs": 0.5862262166666666,
       "phasesMs": {
-        "broad phase": 0.004460856,
-        "continuous": 0.001942376,
-        "islands": 0.000806564,
-        "narrow phase": 0.001015528,
-        "prepare": 0.015942788,
-        "restitution": 0.009394512,
-        "substeps": 0.546367072
+        "broad phase": 0.0041852366666666665,
+        "continuous": 0.0019353299999999999,
+        "islands": 0.00080361,
+        "narrow phase": 0.00105747,
+        "prepare": 0.016008293333333333,
+        "restitution": 0.009457596666666667,
+        "substeps": 0.5525685133333333
       }
     },
     "solver2d card house": {
-      "fingerprint": "4fbd38eef3730b31",
+      "fingerprint": "ea7d1528ea6e2a5e",
       "quality": {
         "levels": {
           "value": 3,
           "unit": ""
         },
         "worst drift": {
-          "value": 0.05576265490251589,
+          "value": 0.14162818999455504,
           "unit": "mm"
         }
       },
-      "stepMs": 0.08392965714285715,
+      "stepMs": 0.08783918095238095,
       "phasesMs": {
-        "broad phase": 0.0016234914285714287,
-        "continuous": 0.0006242857142857143,
-        "islands": 0.00016634285714285714,
-        "narrow phase": 0.02821218285714286,
-        "prepare": 0.005434262857142857,
-        "restitution": 0.0008903542857142858,
-        "substeps": 0.046826508571428574
+        "broad phase": 0.0016421619047619048,
+        "continuous": 0.0006579095238095239,
+        "islands": 0.0001777666666666667,
+        "narrow phase": 0.027161838095238092,
+        "prepare": 0.005864728571428571,
+        "restitution": 0.000954247619047619,
+        "substeps": 0.051219719047619044
       }
     },
     "solver2d centered impact": {
-      "fingerprint": "ccfa947ac592a6a4",
+      "fingerprint": "e1bedba8c7512ef8",
       "quality": {
         "bounce": {
-          "value": 1.7398077180601144,
+          "value": 1.7995910348100592,
           "unit": "m/s"
         },
         "lateral drift": {
-          "value": 0.0007475795228636179,
+          "value": 0.0004816933903688758,
           "unit": "mm"
         }
       },
-      "stepMs": 0.006930726666666667,
+      "stepMs": 0.0070184,
       "phasesMs": {
-        "broad phase": 0.00024186666666666667,
-        "continuous": 0.00010059999999999999,
-        "islands": 0.00007826666666666667,
-        "narrow phase": 0.0008808133333333333,
-        "prepare": 0.00075174,
-        "restitution": 0.000316,
-        "substeps": 0.00441984
+        "broad phase": 0.00024150000000000002,
+        "continuous": 0.00010083333333333334,
+        "islands": 0.00007822222222222223,
+        "narrow phase": 0.00097985,
+        "prepare": 0.0007626166666666667,
+        "restitution": 0.0003129444444444444,
+        "substeps": 0.0044241
       }
     },
     "solver2d circle stack": {
-      "fingerprint": "0a3f1b475a777524",
+      "fingerprint": "1a740d7c89ea63b8",
       "quality": {
         "horizontal drift": {
           "value": 0,
           "unit": "mm"
         },
         "top height error": {
-          "value": 7.103344548649915,
+          "value": 7.099453084640217,
           "unit": "mm"
         }
       },
-      "stepMs": 0.004133155,
+      "stepMs": 0.004386412500000001,
       "phasesMs": {
-        "broad phase": 0.0007682750000000001,
-        "continuous": 0.0001083275,
-        "islands": 0.00007675000000000001,
-        "narrow phase": 0.000311125,
-        "prepare": 0.0005085325000000001,
-        "restitution": 0.00018435,
-        "substeps": 0.00205999
+        "broad phase": 0.0007420916666666667,
+        "continuous": 0.00011364583333333334,
+        "islands": 0.00007867291666666667,
+        "narrow phase": 0.00036327083333333334,
+        "prepare": 0.000583125,
+        "restitution": 0.00019571458333333334,
+        "substeps": 0.002192225
       }
     },
     "solver2d confined": {
-      "fingerprint": "421bb7b06f13eb23",
+      "fingerprint": "5349e31e6f75876e",
       "quality": {
         "escaped": {
           "value": 0,
           "unit": ""
         },
         "max speed": {
-          "value": 5.695985977206491,
+          "value": 5.571465777301871,
           "unit": "m/s"
         },
         "row": {
@@ -244,45 +244,45 @@
           "unit": ""
         }
       },
-      "stepMs": 0.482003888,
+      "stepMs": 0.4438929433333333,
       "phasesMs": {
-        "broad phase": 0.04847136,
-        "continuous": 0.00294756,
-        "islands": 0.001493372,
-        "narrow phase": 0.103083644,
-        "prepare": 0.074621552,
-        "restitution": 0.008087508,
-        "substeps": 0.24247100800000002
+        "broad phase": 0.045836836666666665,
+        "continuous": 0.002721836666666667,
+        "islands": 0.0014226100000000002,
+        "narrow phase": 0.09266798333333334,
+        "prepare": 0.06887237,
+        "restitution": 0.00757283,
+        "substeps": 0.22402076333333332
       }
     },
     "solver2d double domino": {
-      "fingerprint": "130e3ab1df7a73eb",
+      "fingerprint": "00cfdb3e173939da",
       "quality": {
         "fallen": {
           "value": 15,
           "unit": ""
         },
         "time of the last": {
-          "value": 6.016666666666651,
+          "value": 7.349999999999979,
           "unit": "s"
         }
       },
-      "stepMs": 0.11528807875,
+      "stepMs": 0.11550660104166667,
       "phasesMs": {
-        "broad phase": 0.00183274875,
-        "continuous": 0.00070396875,
-        "islands": 0.00020990124999999997,
-        "narrow phase": 0.0206642175,
-        "prepare": 0.00883972875,
-        "restitution": 0.0019020525,
-        "substeps": 0.08095218125
+        "broad phase": 0.0018144020833333334,
+        "continuous": 0.0004748583333333333,
+        "islands": 0.000212453125,
+        "narrow phase": 0.02064351979166667,
+        "prepare": 0.009059655208333333,
+        "restitution": 0.0019143895833333333,
+        "substeps": 0.08119891145833333
       }
     },
     "solver2d far chain": {
-      "fingerprint": "7569d5ae36a9d526",
+      "fingerprint": "920bc3620f9389f9",
       "quality": {
         "far deviation": {
-          "value": 1.0331229789970546e-7,
+          "value": 1.0814722984127874e-7,
           "unit": "mm"
         },
         "finite": {
@@ -290,26 +290,26 @@
           "unit": ""
         },
         "worst gap": {
-          "value": 25.937047921567068,
+          "value": 20.40608155134376,
           "unit": "mm"
         }
       },
-      "stepMs": 0.6462906420000001,
+      "stepMs": 0.6553974216666667,
       "phasesMs": {
-        "broad phase": 0.051685273999999996,
-        "continuous": 0.017276807999999998,
-        "islands": 0.000647306,
-        "narrow phase": 0.010573994000000001,
-        "prepare": 0.014943628,
-        "restitution": 0.004993612,
-        "substeps": 0.545955958
+        "broad phase": 0.047766336666666666,
+        "continuous": 0.017236493333333335,
+        "islands": 0.0006970199999999999,
+        "narrow phase": 0.009058186666666666,
+        "prepare": 0.015384613333333332,
+        "restitution": 0.0051592700000000005,
+        "substeps": 0.5598622316666667
       }
     },
     "solver2d far pyramid": {
-      "fingerprint": "9a28b30be3a8991b",
+      "fingerprint": "27a026a05e4bed38",
       "quality": {
         "far deviation": {
-          "value": 8.907780632216337,
+          "value": 0.6805923984898046,
           "unit": "mm"
         },
         "worst drift": {
@@ -317,45 +317,45 @@
           "unit": "mm"
         }
       },
-      "stepMs": 2.8456944539999998,
+      "stepMs": 3.416486503333333,
       "phasesMs": {
-        "broad phase": 0.087139968,
-        "continuous": 0.00620242,
-        "islands": 0.003377798,
-        "narrow phase": 0.5585856760000001,
-        "prepare": 0.22202198,
-        "restitution": 0.037133066,
-        "substeps": 1.9297350340000001
+        "broad phase": 0.08273485166666666,
+        "continuous": 0.007173518333333333,
+        "islands": 0.0038471699999999996,
+        "narrow phase": 0.6604326416666667,
+        "prepare": 0.2593133266666667,
+        "restitution": 0.042551313333333333,
+        "substeps": 2.3586961066666667
       }
     },
     "solver2d far recovery": {
-      "fingerprint": "998f0b0d592fb07d",
+      "fingerprint": "5d76653bd827d421",
       "quality": {
         "far deviation": {
-          "value": 0.00036292906023460486,
+          "value": 0.00027029356816151974,
           "unit": "mm"
         },
         "max speed": {
-          "value": 3.5716880471398262,
+          "value": 3.5794401735540036,
           "unit": "m/s"
         }
       },
-      "stepMs": 0.5423482933333333,
+      "stepMs": 0.5060772611111111,
       "phasesMs": {
-        "broad phase": 0.006252366666666667,
-        "continuous": 0.0008281133333333333,
-        "islands": 0.0005372066666666667,
-        "narrow phase": 0.16870949666666665,
-        "prepare": 0.03308945666666667,
-        "restitution": 0.004388276666666667,
-        "substeps": 0.32827197333333336
+        "broad phase": 0.006102769444444445,
+        "continuous": 0.0007853972222222222,
+        "islands": 0.0005214444444444444,
+        "narrow phase": 0.16014925833333335,
+        "prepare": 0.030216883333333333,
+        "restitution": 0.004052822222222223,
+        "substeps": 0.30395435
       }
     },
     "solver2d far stack": {
-      "fingerprint": "9bdfc2ae4956f529",
+      "fingerprint": "11ea1fce583a161e",
       "quality": {
         "far deviation": {
-          "value": 0.11290130794691286,
+          "value": 0.8869082560041711,
           "unit": "mm"
         },
         "worst drift": {
@@ -363,45 +363,45 @@
           "unit": "mm"
         }
       },
-      "stepMs": 0.018295106000000002,
+      "stepMs": 0.016550343333333332,
       "phasesMs": {
-        "broad phase": 0.000473244,
-        "continuous": 0.00014394,
-        "islands": 0.00010472,
-        "narrow phase": 0.003934344,
-        "prepare": 0.0016116939999999999,
-        "restitution": 0.000529246,
-        "substeps": 0.011373557999999999
+        "broad phase": 0.000469625,
+        "continuous": 0.00013216833333333332,
+        "islands": 0.00009938333333333334,
+        "narrow phase": 0.0034522449999999996,
+        "prepare": 0.0015034016666666667,
+        "restitution": 0.0004838066666666666,
+        "substeps": 0.010284610000000001
       }
     },
     "solver2d friction ramp": {
-      "fingerprint": "e49861060e0a7f62",
+      "fingerprint": "2f29997fb3f6f207",
       "quality": {
         "sliding error": {
-          "value": 6.0675788535160535,
+          "value": 5.056316187546095,
           "unit": "mm"
         },
         "stopped slide": {
-          "value": 0,
+          "value": 2.446734066676593e-13,
           "unit": "mm"
         }
       },
-      "stepMs": 0.028031592,
+      "stepMs": 0.0278904,
       "phasesMs": {
-        "broad phase": 0.001023616,
-        "continuous": 0.00017544000000000001,
-        "islands": 0.00010688,
-        "narrow phase": 0.011025952,
-        "prepare": 0.002257776,
-        "restitution": 0.00071656,
-        "substeps": 0.012594568
+        "broad phase": 0.0008240733333333333,
+        "continuous": 0.0001772,
+        "islands": 0.0001004,
+        "narrow phase": 0.01078358,
+        "prepare": 0.0023112266666666667,
+        "restitution": 0.0007275333333333334,
+        "substeps": 0.012834586666666667
       }
     },
     "solver2d high mass ratio 1": {
-      "fingerprint": "e7874f6ac25fd537",
+      "fingerprint": "2556598fc959e80d",
       "quality": {
         "heavy cube sag": {
-          "value": 127.99081789071032,
+          "value": 127.56313513180118,
           "unit": "mm"
         },
         "layers": {
@@ -409,115 +409,115 @@
           "unit": ""
         },
         "worst drift": {
-          "value": 105.79202475015144,
+          "value": 88.69691065809597,
           "unit": "mm"
         }
       },
-      "stepMs": 1.698726344,
+      "stepMs": 1.7505143300000001,
       "phasesMs": {
-        "broad phase": 0.01593834,
-        "continuous": 0.002268616,
-        "islands": 0.00188574,
-        "narrow phase": 0.562861172,
-        "prepare": 0.11869384399999999,
-        "restitution": 0.014986652,
-        "substeps": 0.981310976
+        "broad phase": 0.01380236,
+        "continuous": 0.00239012,
+        "islands": 0.0017529133333333332,
+        "narrow phase": 0.4902900233333333,
+        "prepare": 0.12939972333333333,
+        "restitution": 0.01589753,
+        "substeps": 1.0962155533333333
       }
     },
     "solver2d high mass ratio 2": {
-      "fingerprint": "b0c580b92f03cacf",
+      "fingerprint": "35f80b29687cde2f",
       "quality": {
         "bounce": {
-          "value": 2.2252620543727213,
+          "value": 2.0355465723505186,
           "unit": "m/s"
         },
         "slab sag": {
-          "value": 67.77438017502391,
+          "value": 67.63919875990432,
           "unit": "mm"
         },
         "small cubes drift": {
-          "value": 21.56214604243897,
+          "value": 16.468452377556567,
           "unit": "mm"
         },
         "small cubes into ground": {
-          "value": 577.2579911571269,
+          "value": 530.0366269782514,
           "unit": "mm"
         }
       },
-      "stepMs": 0.017935904,
+      "stepMs": 0.015759786666666664,
       "phasesMs": {
-        "broad phase": 0.00041252,
-        "continuous": 0.00019628,
-        "islands": 0.0000992,
-        "narrow phase": 0.005752452,
-        "prepare": 0.001354568,
-        "restitution": 0.000573644,
-        "substeps": 0.009424
+        "broad phase": 0.0003818066666666667,
+        "continuous": 0.00015863333333333333,
+        "islands": 0.00009056666666666667,
+        "narrow phase": 0.004262806666666666,
+        "prepare": 0.0012759066666666666,
+        "restitution": 0.0005415,
+        "substeps": 0.0089258
       }
     },
     "solver2d high mass ratio 3": {
-      "fingerprint": "162be214ceca1077",
+      "fingerprint": "16fc3d89762c7f2b",
       "quality": {
         "bounce": {
-          "value": 2.2253312335268416,
+          "value": 2.035546593114035,
           "unit": "m/s"
         },
         "slab sag": {
-          "value": 67.77361632275891,
+          "value": 67.63920297683335,
           "unit": "mm"
         },
         "small cubes drift": {
-          "value": 21.520070758926067,
+          "value": 16.468453893118642,
           "unit": "mm"
         },
         "small cubes into ground": {
-          "value": 577.2579914400629,
+          "value": 530.0366268830902,
           "unit": "mm"
         }
       },
-      "stepMs": 0.018962556,
+      "stepMs": 0.016582363333333332,
       "phasesMs": {
-        "broad phase": 0.00039088,
-        "continuous": 0.00017580000000000002,
-        "islands": 0.00009392399999999999,
-        "narrow phase": 0.006965624,
-        "prepare": 0.001326616,
-        "restitution": 0.0005552399999999999,
-        "substeps": 0.009322272
+        "broad phase": 0.00037723333333333336,
+        "continuous": 0.00014847,
+        "islands": 0.00008957,
+        "narrow phase": 0.005100736666666667,
+        "prepare": 0.00129302,
+        "restitution": 0.0005405433333333334,
+        "substeps": 0.008910086666666667
       }
     },
     "solver2d joint grid": {
-      "fingerprint": "3bf73d7661991d94",
+      "fingerprint": "fc6397aa108a1b61",
       "quality": {
         "finite": {
           "value": 1,
           "unit": ""
         },
         "max speed": {
-          "value": 30.115023171399358,
+          "value": 29.677462010412945,
           "unit": "m/s"
         },
         "worst gap": {
-          "value": 88.35962353634609,
+          "value": 71.45402387483796,
           "unit": "mm"
         }
       },
-      "stepMs": 4.44351414,
+      "stepMs": 4.297956633333333,
       "phasesMs": {
-        "broad phase": 0.8097767066666667,
-        "continuous": 0.06023162000000001,
-        "islands": 0.00831516,
-        "narrow phase": 0.2033266,
-        "prepare": 0.25451162,
-        "restitution": 0.0297918,
-        "substeps": 3.07573754
+        "broad phase": 0.7044892944444444,
+        "continuous": 0.04431798888888889,
+        "islands": 0.008377738888888889,
+        "narrow phase": 0.18656302222222224,
+        "prepare": 0.2509896555555555,
+        "restitution": 0.030165805555555557,
+        "substeps": 3.071167677777778
       }
     },
     "solver2d overlap recovery": {
-      "fingerprint": "5bbb7588f8e57051",
+      "fingerprint": "d0e49c5c8f23fdb8",
       "quality": {
         "final overlap": {
-          "value": 3.321096845759746,
+          "value": 3.5904768847053634,
           "unit": "mm"
         },
         "layers": {
@@ -525,96 +525,96 @@
           "unit": ""
         },
         "max speed": {
-          "value": 3.5716880409799106,
+          "value": 3.579440180143181,
           "unit": "m/s"
         }
       },
-      "stepMs": 0.31934376400000003,
+      "stepMs": 0.30256958666666667,
       "phasesMs": {
-        "broad phase": 0.004773896,
-        "continuous": 0.000481972,
-        "islands": 0.00036328,
-        "narrow phase": 0.101049792,
-        "prepare": 0.019754956,
-        "restitution": 0.002655388,
-        "substeps": 0.19003628
+        "broad phase": 0.004613256666666667,
+        "continuous": 0.00045770666666666664,
+        "islands": 0.0003148033333333333,
+        "narrow phase": 0.09700434333333334,
+        "prepare": 0.01850401,
+        "restitution": 0.00243612,
+        "substeps": 0.17902811333333332
       }
     },
     "solver2d pyramid": {
-      "fingerprint": "6966ec7612fd5700",
+      "fingerprint": "040fe6c881f7d11d",
       "quality": {
         "layers": {
           "value": 8,
           "unit": ""
         },
         "worst drift": {
-          "value": 1.45745153162969,
+          "value": 1.3984703091777932,
           "unit": "mm"
         }
       },
-      "stepMs": 1.170504028,
+      "stepMs": 1.1881094466666666,
       "phasesMs": {
-        "broad phase": 0.024777076000000002,
-        "continuous": 0.001236692,
-        "islands": 0.0012278880000000001,
-        "narrow phase": 0.371713392,
-        "prepare": 0.090282104,
-        "restitution": 0.008843400000000001,
-        "substeps": 0.6716893119999999
+        "broad phase": 0.025294006666666667,
+        "continuous": 0.00136154,
+        "islands": 0.0012782466666666666,
+        "narrow phase": 0.32590651,
+        "prepare": 0.09391947333333334,
+        "restitution": 0.009792363333333333,
+        "substeps": 0.72968929
       }
     },
     "solver2d rush": {
-      "fingerprint": "13c44583001f28b6",
+      "fingerprint": "0e2d9d71fb7a52f9",
       "quality": {
         "final overlap": {
-          "value": 2.386494028450481,
+          "value": 2.417279648855186,
           "unit": "mm"
         },
         "final speed": {
-          "value": 0.020914631998823915,
+          "value": 0.16259664402005986,
           "unit": "m/s"
         },
         "max speed": {
-          "value": 12.987043356298601,
+          "value": 12.944602038140715,
           "unit": "m/s"
         }
       },
-      "stepMs": 0.066552784,
+      "stepMs": 0.06329681,
       "phasesMs": {
-        "broad phase": 0.017071128,
-        "continuous": 0.00398104,
-        "islands": 0.0008597240000000001,
-        "narrow phase": 0.00011212,
-        "prepare": 0.007568648,
-        "restitution": 0.006720804,
-        "substeps": 0.03012368
+        "broad phase": 0.013700053333333333,
+        "continuous": 0.0039777599999999995,
+        "islands": 0.00083827,
+        "narrow phase": 0.00008236666666666666,
+        "prepare": 0.00768381,
+        "restitution": 0.006660816666666667,
+        "substeps": 0.030232233333333334
       }
     },
     "solver2d single box": {
-      "fingerprint": "7ac48fd94a2b753c",
+      "fingerprint": "6ff146d7621f506c",
       "quality": {
         "height error": {
-          "value": 0.06902504482564353,
+          "value": 0.06902504565653445,
           "unit": "mm"
         },
         "rest drift": {
-          "value": 0.00010860480059715627,
+          "value": 0.00010093712410341737,
           "unit": "mm"
         }
       },
-      "stepMs": 0.004723846666666667,
+      "stepMs": 0.002994583333333333,
       "phasesMs": {
-        "broad phase": 0.00027573333333333333,
-        "continuous": 0.00014033333333333332,
-        "islands": 0.0001222,
-        "narrow phase": 0.00025140666666666667,
-        "prepare": 0.0004670066666666667,
-        "restitution": 0.00026307333333333333,
-        "substeps": 0.0030406266666666666
+        "broad phase": 0.00015972222222222223,
+        "continuous": 0.000077,
+        "islands": 0.0000665,
+        "narrow phase": 0.0001747777777777778,
+        "prepare": 0.00031716666666666666,
+        "restitution": 0.00018239444444444444,
+        "substeps": 0.001903411111111111
       }
     },
     "solver2d stretched chain": {
-      "fingerprint": "f6e92f3665ce4bd4",
+      "fingerprint": "9f63a900d330ab9e",
       "quality": {
         "final gap": {
           "value": 0.07178605861213327,
@@ -625,7 +625,7 @@
           "unit": ""
         },
         "max speed": {
-          "value": 254.50238414789507,
+          "value": 256.8677345941416,
           "unit": "m/s"
         },
         "rest gap": {
@@ -633,22 +633,22 @@
           "unit": "mm"
         }
       },
-      "stepMs": 0.043703542,
+      "stepMs": 0.044242175,
       "phasesMs": {
-        "broad phase": 0.003121604,
-        "continuous": 0.00040764,
-        "islands": 0.00017752000000000002,
-        "narrow phase": 0.000200042,
-        "prepare": 0.001950956,
-        "restitution": 0.00043378,
-        "substeps": 0.037176274
+        "broad phase": 0.0030517966666666666,
+        "continuous": 0.0003975683333333333,
+        "islands": 0.000201055,
+        "narrow phase": 0.00011893499999999999,
+        "prepare": 0.0019251283333333333,
+        "restitution": 0.00043979,
+        "substeps": 0.0378815
       }
     },
     "solver2d vertical stack": {
-      "fingerprint": "51fef4fd3c94bf8e",
+      "fingerprint": "48a4cc8b0c742495",
       "quality": {
         "horizontal drift": {
-          "value": 2.845671443000555,
+          "value": 3.01593245638026,
           "unit": "mm"
         },
         "layers": {
@@ -656,61 +656,61 @@
           "unit": ""
         }
       },
-      "stepMs": 0.022261464,
+      "stepMs": 0.020979173333333333,
       "phasesMs": {
-        "broad phase": 0.000911124,
-        "continuous": 0.0001988,
-        "islands": 0.00012328,
-        "narrow phase": 0.0049292,
-        "prepare": 0.00218402,
-        "restitution": 0.000839008,
-        "substeps": 0.012949312000000001
+        "broad phase": 0.0009151766666666666,
+        "continuous": 0.0002032,
+        "islands": 0.00013230333333333333,
+        "narrow phase": 0.0037009933333333332,
+        "prepare": 0.0022184033333333335,
+        "restitution": 0.00081438,
+        "substeps": 0.012852416666666667
       }
     },
     "solver2d warm start energy": {
-      "fingerprint": "8dcfb49e8c691bf3",
+      "fingerprint": "64080265c973a518",
       "quality": {
         "overshoot": {
           "value": 0,
           "unit": "mm"
         }
       },
-      "stepMs": 0.0036926679999999996,
+      "stepMs": 0.0037194666666666666,
       "phasesMs": {
-        "broad phase": 0.00024568,
-        "continuous": 0.000091444,
-        "islands": 0.00007408,
-        "narrow phase": 0.00032404,
-        "prepare": 0.00057076,
-        "restitution": 0.000163084,
-        "substeps": 0.002104612
+        "broad phase": 0.00024100333333333334,
+        "continuous": 0.0000922,
+        "islands": 0.00007443333333333333,
+        "narrow phase": 0.00032637,
+        "prepare": 0.0005691,
+        "restitution": 0.0001652,
+        "substeps": 0.0021346566666666667
       }
     },
     "terrain piles": {
-      "fingerprint": "4a6b6d3833b795ba",
+      "fingerprint": "ca16c8f217a79890",
       "quality": {
         "median landing depth": {
-          "value": 7.875508690151446,
+          "value": 7.26281832420491,
           "unit": "mm"
         },
         "worst landing depth": {
-          "value": 17.85679629331417,
+          "value": 12.82998497579694,
           "unit": "mm"
         },
         "worst resting depth": {
-          "value": 7.342632951171865,
+          "value": 7.345867902704917,
           "unit": "mm"
         }
       },
-      "stepMs": 3.997912273,
+      "stepMs": 3.070904823333333,
       "phasesMs": {
-        "broad phase": 0.031085574,
-        "continuous": 1.954000463,
-        "islands": 0.0015134764999999999,
-        "narrow phase": 1.0432447784999999,
-        "prepare": 0.089018852,
-        "restitution": 0.013083258,
-        "substeps": 0.865058801
+        "broad phase": 0.02748282375,
+        "continuous": 1.4693527233333332,
+        "islands": 0.0014843529166666668,
+        "narrow phase": 0.9272526575000001,
+        "prepare": 0.08509789708333333,
+        "restitution": 0.0127703225,
+        "substeps": 0.5466390391666667
       }
     }
   }
diff --git a/bench/current.go b/bench/current.go
index d7ce7b9..8d89f4a 100644
--- a/bench/current.go
+++ b/bench/current.go
@@ -38,6 +38,12 @@ func narrow(a, b *actor.RigidBody) (bool, mgl64.Vec3, float64, int) {
 	return true, m.Normal, -m.MinSeparation(), m.Count
 }
 
+// the setting of Feather for the games: 60 Hz, 8 sub-steps
+const (
+	dt       = 1.0 / 60
+	substeps = 8
+)
+
 func world(workers int) *feather.World {
 	return &feather.World{
 		Gravity:  mgl64.Vec3{0, -g, 0},
diff --git a/bench/main.go b/bench/main.go
index 1235421..b727a7b 100644
--- a/bench/main.go
+++ b/bench/main.go
@@ -7,7 +7,8 @@
 //	go run . -update                                          # write baseline.json, after a wanted change
 //	go run . -scenes ; go run . -compare                      # the scenes of Solver2D (reference.go)
 //
-// Every scene runs at AkmonEngine's rate: 50 Hz, 12 sub-steps, one worker.
+// Every scene runs at the setting of each version, one worker: 60 Hz with 8 sub-steps for the working tree (the
+// setting of Feather for the games), 50 Hz with 12 sub-steps for v0.2.0 (the setting AkmonEngine ran it with).
 package main
 
 import (
@@ -24,9 +25,7 @@ import (
 )
 
 const (
-	dt       = 1.0 / 50
-	substeps = 12
-	g        = 9.81
+	g = 9.81
 )
 
 func body(w *feather.World, t actor.Transform, s actor.ShapeInterface, typ actor.BodyType, mu, e float64) *actor.RigidBody {
@@ -182,7 +181,7 @@ func force() {
 	b := body(w, tr(mgl64.Vec3{}, mgl64.QuatIdent()), &actor.Sphere{Radius: 0.25}, actor.BodyTypeDynamic, 0, 0)
 	m := b.Material.GetMass()
 	F := 10.0
-	for i := 0; i < 50; i++ {
+	for i := 0; i < int(math.Round(1/dt)); i++ {
 		b.AddForce(mgl64.Vec3{F, 0, 0})
 		w.Step(dt)
 	}
diff --git a/bench/scenes/adapter_current.go b/bench/scenes/adapter_current.go
index 54ee57e..e084ded 100644
--- a/bench/scenes/adapter_current.go
+++ b/bench/scenes/adapter_current.go
@@ -43,6 +43,13 @@ func moved(b *actor.RigidBody) {
 	b.UpdateAABB()
 }
 
+// the setting of Feather for the games: 60 Hz (the default rate of Box3D, the reference, which runs its default 4
+// substeps) with 8 substeps
+const (
+	Dt       = 1.0 / 60
+	substeps = 8
+)
+
 func newWorld() *feather.World {
 	return &feather.World{
 		Gravity:  mgl64.Vec3{0, -gravity, 0},
diff --git a/bench/scenes/adapter_v020.go b/bench/scenes/adapter_v020.go
index 244e2d7..3544645 100644
--- a/bench/scenes/adapter_v020.go
+++ b/bench/scenes/adapter_v020.go
@@ -39,6 +39,12 @@ func ball(w *feather.World, a, b *actor.RigidBody, anchor mgl64.Vec3) {
 // moved: v0.2.0 computes the AABB at each step
 func moved(b *actor.RigidBody) {}
 
+// the setting AkmonEngine ran v0.2.0 with: 50 Hz, 12 substeps (v0.2.0 has no default)
+const (
+	Dt       = 1.0 / 50
+	substeps = 12
+)
+
 func newWorld() *feather.World {
 	return &feather.World{
 		Gravity:     mgl64.Vec3{0, -gravity, 0},
diff --git a/bench/scenes/scenes.go b/bench/scenes/scenes.go
index f7d835a..98cfbbb 100644
--- a/bench/scenes/scenes.go
+++ b/bench/scenes/scenes.go
@@ -16,14 +16,10 @@ import (
 	"github.com/go-gl/mathgl/mgl64"
 )
 
-const (
-	// Dt of a step (s): the default rate of Box3D, the reference. 8 substeps: the setting of Feather for the games
-	// (Box3D runs its default, 4). The contacts are springs of 30 Hz whatever the substeps: a light body under a load
-	// sinks by (mass ratio) g / ω² at rest, and more substeps make the stacks, the impacts and the far scenes better
-	Dt       = 1.0 / 60
-	substeps = 8
-	gravity  = 9.81
-)
+// Each version runs at its own setting (adapter_current.go, adapter_v020.go): Dt of a step and the substeps.
+// The contacts are springs of 30 Hz whatever the substeps: a light body under a load sinks by (mass ratio) g / ω² at
+// rest, and more substeps make the stacks, the impacts and the far scenes better
+const gravity = 9.81
 
 // Size of a scene
 type Size int
diff --git a/bench/v020.go b/bench/v020.go
index eb1cb4d..86ed3e8 100644
--- a/bench/v020.go
+++ b/bench/v020.go
@@ -45,6 +45,12 @@ func regressions(update bool) bool {
 	return false
 }
 
+// the setting AkmonEngine ran v0.2.0 with: 50 Hz, 12 sub-steps (v0.2.0 has no default)
+const (
+	dt       = 1.0 / 50
+	substeps = 12
+)
+
 func world(workers int) *feather.World {
 	return &feather.World{
 		Gravity:     mgl64.Vec3{0, -g, 0},
diff --git a/constraint/contact.go b/constraint/contact.go
index 3d6a249..2815ae7 100644
--- a/constraint/contact.go
+++ b/constraint/contact.go
@@ -17,6 +17,12 @@ type ContactPoint struct {
 	// NormalImpulse applied by the solver during the last step (N·s), to warm start the next step
 	NormalImpulse float64
 
+	// Impact in progress, kept from a step to the next: the approach velocity when the point started to hit (m/s,
+	// 0 without impact) and the normal impulse of its compression so far (N·s). The point bounces once the
+	// compression is over, which can be during the next step when the impact starts at the very end of a step
+	ImpactVelocity     float64
+	CompressionImpulse float64
+
 	// LocalAnchorA is the point on the surface of A, in the local space of A, LocalAnchorB the point on the
 	// surface of B, in the local space of B. They find the same point in the next step (warm starting),
 	// and move the contact with the bodies (pair cache)
diff --git a/solver.go b/solver.go
index b23da88..e3e702d 100644
--- a/solver.go
+++ b/solver.go
@@ -152,6 +152,9 @@ type contactPoint struct {
 	normalImpulse      float64
 	totalNormalImpulse float64 // the normal impulse of the step: the impulse which stopped the point, for the restitution
 	normalVelocity     float64 // before the solver, for the restitution
+	// the impact in progress (see ContactPoint): its approach velocity, and the impulse of its compression so far
+	impactVelocity     float64
+	compressionImpulse float64
 	leverArm           float64 // distance to the friction center: the twist friction it can hold
 }
 
@@ -403,8 +406,9 @@ func (s *solver) prepareConstraint(i int) {
 		cp.baseSeparation = point.Separation - cp.coreB.Sub(cp.coreA).Dot(c.normal)
 		cp.normal = makeJacobian(stateA, stateB, cp.rA, cp.rB, c.normal)
 
-		// Warm starting: the impulses of the previous step
+		// Warm starting: the impulses of the previous step, and the impact in progress
 		cp.normalImpulse = point.NormalImpulse
+		cp.impactVelocity, cp.compressionImpulse = point.ImpactVelocity, point.CompressionImpulse
 		cp.normalVelocity = relativeVelocity(stateA, stateB, cp.rA, cp.rB).Dot(c.normal)
 	}
 	c.prepareFriction(stateA, stateB, staticFriction, dynamicFriction)
@@ -1101,10 +1105,13 @@ func clampDisk(impulse *[2]float64, radius float64) {
 }
 
 // ========== RESTITUTION ==========
-// restitution, after the substeps: a point which hit faster than RestitutionThreshold bounces. Its impulse goes towards
-// the velocity -restitution * its velocity before the step (Newton), and is at most restitution times the impulse which
-// stopped it, its normal impulse of the step (Poisson's hypothesis, W. J. Stronge, Impact Mechanics): a pile of bodies
-// doesn't give back more than it absorbed
+// restitution, after the substeps: a point which hit faster than RestitutionThreshold bounces once its compression is
+// over (it doesn't approach anymore). Its impulse goes towards the velocity -restitution * its approach velocity
+// (Newton), and is at most restitution times the impulse of the compression (Poisson's hypothesis, W. J. Stronge,
+// Impact Mechanics): a pile of bodies doesn't give back more than it absorbed. An impact which starts at the very end of
+// a step is compressed over 2 steps: the point keeps its approach velocity and its compression impulse, and bounces at
+// the end of the second step, with the whole impulse. Bounced at the end of the first step, it would give back
+// restitution times a fraction of the impulse only
 func (s *solver) restitution() {
 	s.solveConstraints(s.jobs.restitution, nil)
 }
@@ -1116,15 +1123,24 @@ func (s *solver) restitutionConstraint(c *contactConstraint) {
 	stateA, stateB := s.state(c.indexA), s.state(c.indexB)
 	for j := 0; j < c.pointsCount; j++ {
 		cp := &c.points[j]
-		if cp.normalVelocity >= -RestitutionThreshold || cp.totalNormalImpulse <= 0 {
-			continue
+		if cp.impactVelocity == 0 {
+			if cp.normalVelocity >= -RestitutionThreshold || cp.totalNormalImpulse <= 0 {
+				continue
+			}
+			cp.impactVelocity = cp.normalVelocity
 		}
+		cp.compressionImpulse += cp.totalNormalImpulse
 		velocity := cp.normal.velocity(stateA, stateB, c.normal)
-		newton := -cp.normal.mass * (velocity + c.restitution*cp.normalVelocity)
-		poisson := c.restitution * cp.totalNormalImpulse
+		if velocity < -actor.DefaultSleepSpeed {
+			// still approaching: the compression goes on in the next step
+			continue
+		}
+		newton := -cp.normal.mass * (velocity + c.restitution*cp.impactVelocity)
+		poisson := c.restitution * cp.compressionImpulse
 		if impulse := math.Min(newton, poisson); impulse > 0 {
 			cp.addNormalImpulse(stateA, stateB, c.normal, impulse)
 		}
+		cp.impactVelocity, cp.compressionImpulse = 0, 0
 	}
 }
 
@@ -1140,6 +1156,7 @@ func (s *solver) storeImpulsesConstraint(i int) {
 		point := &c.manifold.Points[j]
 		cp := &c.points[j]
 		point.NormalImpulse = cp.normalImpulse
+		point.ImpactVelocity, point.CompressionImpulse = cp.impactVelocity, cp.compressionImpulse
 	}
 	c.manifold.FrictionImpulse = c.tangents[0].Mul(c.frictionImpulse[0]).Add(c.tangents[1].Mul(c.frictionImpulse[1]))
 	c.manifold.TwistImpulse = c.twistImpulse
diff --git a/world.go b/world.go
index f64d284..e71c779 100644
--- a/world.go
+++ b/world.go
@@ -513,6 +513,7 @@ func warmStartPair(manifolds, previous []constraint.Manifold) {
 				used[closestManifold][closest] = true
 				point := &previous[closestManifold].Points[closest]
 				manifold.Points[j].NormalImpulse = point.NormalImpulse
+				manifold.Points[j].ImpactVelocity, manifold.Points[j].CompressionImpulse = point.ImpactVelocity, point.CompressionImpulse
 				if source < 0 {
 					source = closestManifold
 				}
diff --git a/world_physics_test.go b/world_physics_test.go
index 19dd473..94adb2c 100644
--- a/world_physics_test.go
+++ b/world_physics_test.go
@@ -11,11 +11,10 @@ import (
 	"github.com/go-gl/mathgl/mgl64"
 )
 
-// Physical scenarios with a known answer, at the rate AkmonEngine runs Feather:
-// 50 Hz, 12 sub-steps.
+// Physical scenarios with a known answer, at the setting of Feather for the games: 60 Hz, 8 sub-steps.
 const (
-	sceneDt       = 1.0 / 50
-	sceneSubsteps = 12
+	sceneDt       = 1.0 / 60
+	sceneSubsteps = 8
 	sceneGravity  = 9.81
 	cubeHalf      = 0.25
 )
@@ -189,13 +188,14 @@ func TestBounceRestitution(t *testing.T) {
 		ground := addGround(w, 0)
 		ground.Material.Restitution = e
 		ball := addBody(w, mgl64.Vec3{0, 1 + cubeHalf, 0}, mgl64.QuatIdent(), &actor.Sphere{Radius: cubeHalf}, actor.BodyTypeDynamic, 0, e)
+		// the apex of the rebound: the height reached while going up after the hit
 		hit, apex := false, 0.0
 		simulate(w, 2.5, func() {
 			h := ball.Transform.Position.Y() - cubeHalf
 			if h < 0.01 {
 				hit = true
 			}
-			if hit {
+			if hit && ball.Velocity.Y() > 0 {
 				apex = math.Max(apex, h)
 			}
 		})
@@ -217,7 +217,7 @@ func TestForcesAreSI(t *testing.T) {
 	m := ball.Material.GetMass()
 	inertia := ball.InertiaLocal.At(0, 0)
 	const force, torque = 10.0, 3.0
-	for i := 0; i < 50; i++ {
+	for i := 0; i < int(math.Round(1/sceneDt)); i++ {
 		ball.AddForce(mgl64.Vec3{force, 0, 0})
 		ball.AddTorque(mgl64.Vec3{0, torque, 0})
 		w.Step(sceneDt)
@@ -250,8 +250,12 @@ func TestTumblingKeepsAngularMomentum(t *testing.T) {
 			flipped = true
 		}
 	})
-	if drift := momentum().Sub(l0).Len() / l0.Len(); drift > 0.01 {
-		t.Errorf("angular momentum drifted by %.2f%% over 10 s", drift*100)
+	// the gyroscopic torque is integrated to the first order: each substep h can lose |L| (ω h)² at most, as the
+	// invariants (measure.gyroscopicError); over 10 s, T ω² h. Measured: 30 times under the bound, linear in h
+	h := sceneDt / sceneSubsteps
+	bound := 10 * box.AngularVelocity.LenSqr() * h
+	if drift := momentum().Sub(l0).Len() / l0.Len(); drift > bound {
+		t.Errorf("angular momentum drifted by %.2f%% over 10 s, bound %.1f%%", drift*100, bound*100)
 	}
 	if e := energy(); e > e0*1.001 || e < e0*0.9 {
 		t.Errorf("rotational energy went from %.4f to %.4f J", e0, e)
@@ -270,7 +274,7 @@ func TestDamping(t *testing.T) {
 	ball.Velocity, ball.AngularVelocity = mgl64.Vec3{1, 0, 0}, mgl64.Vec3{0, 0, 1}
 	simulate(w, 1, nil)
 	h := sceneDt / sceneSubsteps
-	steps := float64(50 * sceneSubsteps)
+	steps := math.Round(1/sceneDt) * sceneSubsteps
 	if want := math.Pow(1/(1+h*0.5), steps); math.Abs(ball.Velocity.X()-want) > 1e-9 {
 		t.Errorf("linear speed %.6f, want %.6f", ball.Velocity.X(), want)
 	}