I have a Radeon 4870x2, Intel Quad 9450, Windows 7 with 8GB of ram on a Raptor HD and I was wondering why my game was choppy. Every new game that has come out has had no problems on maximum graphics.
I tried some solutions and they seemed to help, but the biggest one was disabling crossfire. Just go to your catalyst control panel and disable catalyst AI.
I also did some other things, which may or may not have helped:
I right clicked on the game icon, clicked properties and disabled desktop composition and ran the program as an administrator.
Now the game is smooth as silk. I hope the game eventually supports crossfire in a patch, I could only imagine how much faster it will run.
I dont know how to disable SLI on Nvidia cards, but I'd imagine one solution would be to disable one of the cards in your device manager.
I hope this helps some people.