Bug Unity Physics performance degraded since 2020.3.16

It took me a while to figure out what's going on, but long story short 2020.3.16 introduced something which kills Unity Physics performance on heavy scenes, but not Havok's.

16k cubes falling down on the ground.

2020.3.15 and earlier down to 2019.4.32:


2020.3.16 and later up to 2020.3.23:


Same packages, settings, scene, same everything.

2020.3.16 patch notes mention "Burst: Platform updates." and that's my only clue. Why all of a sudden narrow phase starts taking x2.5 time and why DispatchPairs job not only becomes noticeable, yet eating the bulk on the frame's time. This is repo project; in my main one DispatchPairs eats up to 70% of frame time!

Bug case is 1385608 and I wonder has anybody else experienced this ?

 

The bug has been finally accepted, though it's labeled as Hybrid Renderer, not a Physics package. Anyway, I guess once fixed it should boost Physics performance considerably past the 2020.3.15 version.

https://issuetracker.unity3d.com/is...ce-when-using-unity-2020-dot-3-16f1-or-higher