Here is all I've seen so far. These commands should hopefully help your gameplay and FPS in some way.

Shows you how many frames per second you are getting:
/cg_drawFPS 1

Takes off the labels on the top right FPS meter, making the text not so annoying:
/cg_drawFPSlabels 0

Takes off the FPS cap, causing you to have a higher FPS:
/cg_maxFPS 0

Renders less corpses, causing better performance:
/ai_corpseCount 0

Eliminates the emitting of shells, for example, when you shoot:
/cg_brass 0

Increases mouse responsiveness:
/r_gpuSync 2