My setup:
Windows 7 64-bit, with all the latest updates
AMD Phenom II 955 (4 x 3,2 GhZ)
4 GB Kingston HyperX Blu 1600 MhZ DDR3
Sapphire Radeon HD 5830 Extreme, with latest drivers
500 GB HDD (7200rpm)
Before running the game I uninstalled my AMD Radeon drivers just in case -> rebooted -> cleaned the remaining bits with DriverSweeper -> Rebooted -> Installed the latest AMD Catalyst and Drivers(v. 11.11)
After the opening cinematic the frame rate is about 0.25 frames per seconds. I have tried changing every graphics option, but still the situation stays similar. Any suggestions?