Since 2-3 weeks now I've been unable to play the game because the game stutters every 10-30 seconds. It seems like my FPS drops to 0 for a couple milliseconds in short bursts of 3-4 at a time. Sometimes my FPS just gets regular drops as well for a few seconds. I'm pretty clueless as to what it could be, as I'm only running 40-50 processes when playing and none of those seem to superfluous to the system. I also don't seem to have this problem when running other heavier games like SC2.

OS: Windows 7 Pro SP1 x86
RAM: 2Gb
CPU: DualCore AMD Athlon 64 X2, 2400 MHz (12 x 200) 4600+
GPU: NVIDIA GeForce GT 620 (2048 MB)
GPU Driver: version 320.48 (latest)