CPU slows to a crawl when gaming

[Sandstorm83]

Lately when I've been playing games on my T61, the computer would randomly slow to a crawl for a minute and the FPS drops down significantly.
I would run PC Wizard 2008 and it records the CPU speed at around 300-400 MHz with a Core Load of near 100%. Then a minute later it returns to normal between 800 and 2000 MHz.
This occurs every few minutes only while gaming and I dont know why it happens.

I have a T61 with T7300 and the NVS 140m running Vista x64 and 4GB RAM.

[seungsohn]

Have you tried turning off aero and using the high performance power plan?

[Sandstorm83]

Using the high performance power plan fixed the problem. But it never used to do this in the past when using the balanced plan.