It's weird when you think about it, considering how GPU intensive it seems to be. But it's probably the most CPU limited game around. :\
Just gotta turn on that Ubersampling.

Still, I wouldn't worry too much about 80fps with a stock Sandy Bridge CPU. I'm sure there will be many GPU limited areas in the game, and I'm sure that 680 will still drop below 60fps plenty. At least, that's what I'd assume. No way to know without testing it out. Maybe I'll get around to it some day.