Counter-strike FPS problems

Well playing the game, my FPS averages out to around 40 FPS. Randomely during the game, it drops down to around 10-15 FPS for about a two minute time span. After these two minutes, the FPS shoots back up to its normal range again, but only for another two minutes. This cycle continues as long as i play the game.

Anyone know how to regulate my FPS to the normal 40 FPS zone, and not have it drop every few minutes?

http://www.techspot.com/vb/topic79560.html

You may wanna go through that and try everything on there.