I've just pushed a change to the smoke particle that removes its physics calculations and sets the tps to 6. I found it vastly improved my framerate without any significant change in the visuals or functioning of the smoke grenades. Most importantly, I found I could have 5 smoke grenades going at once without maxing out the allowed particles, which caused other particles (existing smoke or other weapon effects, for instance) to disappear.
The numbers may get changed further, since this is Crystan's field, but this should work until we can find a more permanent solution.