Im having troubles running this game on 3x1 L eyefinity. I have latest driver, Windows 7 64 bit, 8gb ram, 2 gb radeon 5870 eyefinity 6, AMD 1100T x6 OC 3.6 Ghz base 4.2 Ghz Turbo. It runs really slow getting low fps 15<30
Assuming you've already played around with various graphic settings, it could just be the fact that the PC version is a port from the console version and simply not tuned very well. I don't have the game so I can't offer any specific tips.