I haven't seen anyone get this problem. When ever I punch or grab (basically when i press M1 or M2) my game drops from 60fps 50 or 45 fps. It's really annoying because it can put me off enough to mess up kick glitch chains. I recently got the GOG version of the game. PhysX is not the issue. I have a GTX 750ti, i5 4460 and 8GB DDR3 RAM fyi.

Go to where you installed the game and right click the MirrorsEdge.exe and select Properties. Go to the Compatibility tab and check both boxes for "Disable full-screen optimizations" and "Run this program as an administrator".

I don't know if this will help but it might.

That did not work. Any other suggestions. I'll try anything hoping to make the game not shudder

SOLVED: Right, so I fixed it by moving the game to a new hard drive. No shuddering now!