Bad performance with Physics.Processing and impossible to find the reason why.

Hello, i am getting bad performance in the profiler with Physics.processing especially when PhysX.BpSAP.postUpdateWork and PhysX.BpSAP.updateWorkare called. What is causing this ? What can i do to resolve it ?

I am using unity version 2018.4 and i am profiling a build (not playmode in editor).

There is almost no info about this on internet.