On CoD4 ProMod the fps is fully adjustable.
/com_drawfps 1 to show your current fps on the screen.
/com_maxfps 125/250/333 These values give advantages in terms of silent running and strafing. 125 And 250 are allowed in ProMod and 333 is forbidden. If you dont get 250 stable it's best to change it to 125.
If you get stuck at 60fps it is possible that you have "sync every frame" on in your options and you have to turn that off in order to get higher fps.
Ippert :twisted: