My pals over at PlanetHardware, who I actually don't know, have posted an updated Counter-Strike Tweak Guide. Here's a small bit:
Another set of smoke variables refer to how many smoke puffs to use when drawing the smoke effect ('max_smokepuffs X) and whether to draw smoke around weapons (gunsmoke X). To set gunsmoke on, type 'gunsmoke 1' and to turn it off type 'gunsmoke 0'. The default setting for max_smokepuffs is 120 - set this to zero to increase performance, or crank it up to see more of that wonderous smoke effect.Of course, there's plenty more where that came from. That's why it's only a small bit.