Oops, sorry if I jumped to conclusions!
It's going to vary between CPU to CPU but the difference is very negligible.
Comparison between a high end Intel processor (i7-3930k) with a rather low end AMD (Phenom II x4):
The difference between FPS is what, like, 1-2. This is assuming they held every other variable constant, including the GPU. The motherboard and CPU obviously have been changed though.