FYI, unparking cpu cores fixed this sort of issue for me, the game went from an unplayable stuttering mess to 100% completely smooth. I highly recommend trying it if you have cores parked. I used the utility here http://www.coderbag.com/Programming-C/Disable-CPU-Core-Parking-Utility but it can also be done manually. Plenty of others have had success with it. My apologies if this has already been mentioned in this thread. Good luck everybody, I can't express how great I'm finding this game now that it's playing smoothly.
Specs:
Intel Core i7 930 @ 4.1GHz
6GB Corsair XMS3 Dominator
ASUS Rampage III Extreme
SLI Galaxy GTX 780 / Dell
U2711
Creative X-Fi Titanium
512GB Samsung
Windows 7 Home Premium x64