Crysis games have a directx 9 and 10 mode. Gogs desktop shortcuts puts directx 9 mode on the expansions, and 10 on the first game. Check the start menu shortcuts for whichever you prefer

Crysis is 32 and 64 bit while the expansion is only 64 bit. Choose which you prefer. A 32 bit exe has a *32 suffix at the end of an exe in the processes section of task manager but only on a 64 bit os.

Game running slow? Looks like a 24hz bug just do alt+enter a few times till you get full screen 60hz. Needed each time per game boot. Possibly applicable to hdtvs only since they can do a 24hz signal