There is nothing really outstanding showing up in the DxDiag report -- other than the slight disparity in performance between your R7 255 and the minimum Radeon, HD 7850. If you had the game running and didn't accidentally demand high quality settings that the GPU balks at doing, I personally am at a loss here.
Try a Clean Boot diagnostic run, maybe your AV has a new element that is interfering, or some overlay has changed that you aren't aware of.
