I do agree that more\better time-slicing could be part of the solution for bodies. The current time-slicing code was tuned using the samples that where available at the time so it’s not totally surprising that you found some cases where they break. That can be a solution to get you to ship. Our current work is to move off lots of that work from the game thread and we are also working on aggressively reducing the number of Actors\Components. That should be ready when you need it in your next project. I would also recommend that you consider using runtime PCG for scattering smaller objects.
I did find some information on the CreateCommittedResource hitch. We have a private case that discusses lock contention when using Aftermath. Could it be your problem? The problematic CVar is r.GPUCrashDebugging.Aftermath.ResourceTracking. It is turned off by default so this might need further investigation.
The rendering team will want to know the type and size of the texture(s) that is taking long. I would suggest that you add some code to time the duration of CreateCommittedResource and put a breakpoint when it takes more than 10ms. Please open a new case with so it can be assigned to the proper people here.