Thank you for the DxDiag, IMDDK! The system files look pretty solid. There’s some radar preleak errors with SC2, but these generally shouldn’t cause an issue with the performance.
I believe I found something that our team is looking into and its a very high priority from our team. After the patch 4.11.4, they were seeing some performance issues with versus, co-op, and custom 1v1 games. Based on what you were saying here and some other threads, it sounds relevant to this issue.
At the moment, there’s no additional information for the issue, but our team is looking into this. Just curious, have you tried lowering your settings in the mean time to see if it may be a bit more playable?