After last mini patch my screen was stuttering even at 60 FPS i went to video settings and turn off/on every settings and observed the changes, for me it was the Ambient Occlusion . I've turned off and stuttering was gone. I know there are people out there having the same problem after last patch try turn off ambient occlusion. It fixed for me.
I've had ambient occlusion turned off all along, unfortunately I still experience these drops in performance down to 10fps for a few seconds at a time.