I can second this. I’m also on a Threadripper (2950x), 1080ti’s, caching to an SSD, r20, 2.6.46 rs in my case. It’s hit or miss, not every time. I’m simming about 72 frames at the moment. Not particularly heavy sim either.
What I’ve tried:
Turning off the GPU I’m simulating with when rendering (isolating one gpu just for sims). Making sure RS live viewer is not running while I’m simming. Nothing seems to solve it.
There is a known issue that can cause this type of freeze in Redshift. The fix is in Redshift 3.0.12. I’m don’t know when it’s going to be merged into the 2.6 branch.
If 3.0.12 is an option for you, please try this build to check if the freeze you are experiencing is the one that was fixed.