Lag!?

I'm getting lots of lag from crossfire, basically like every 10 seconds, i don't know why. Now before you guys start saying "omg look at system requirements", i have to add that I can play Counter-Strike:Source(The old one anyways), Hl2, hl2e1. They run smoother than crossfire!? I noticed that grenades at one point seem to cause a bit of lag and also radio commands. Can someone help me with this?