Crysis Windows 7 Professional x64 weird framerate issue.?

I've had a legit 64-bit copy of Windows 7 Professional (got it for $30 because I'm a college student) for about 2-3 weeks now. I love it to death, kudos to Microsoft. However I have one annoying issue with Crysis, as well as Crysis: WARHEAD. During gameplay, if I'm facing one way then suddenly turn 180 degrees in any other direction, my FPS drops noticeably for about 2-5 seconds, then boosts back up. It happens almost everywhere in the game where there's AI or particle effects and it's really been bugging me. I've shelled out an assload of money in the past two months just trying to get my PC to run this ******* game. This weird framerate issue is the only thing that stands in my way. I recently updated from an Asus P5n-e SLI with 2 gigs of Crucial Ballistix to new specs which are right here:

BFG Tech GTX 285 2Gb 512-bit video memory

GIGABYTE GA-EP43T-UD3L LGA 775 Intel P43 ATX Intel Motherboard

Crucial Ballistix Tracer 4GB DDR3 1333 PC10600

Intel Core 2 Quad processor clocked at 2.4Ghz with 8mb L2 Cache

500Gb hard drive

700 Watt Antec PSU

I've tried a lot of things. Ranging from disabling visual themes, downloading GameBooster, to forcing certain settings on nVidia manager. I don't have this problem with any other game. Can someone please help? Me want crysis to run well damnit! Lol. Thanks all.