Overall performance is about power/weight.
Gearing improves neither of these.

Gearing will generally improve acceleration times *from zero mph*, but from a roll they may make you SLOWER, depending on what the start speed is. For track/autoX, it all depends on the course.

Lighter flywheel is a fine idea. Stock-weight flywheels are overweight as a crutch to those who don't know how to drive a stick. Lighter is better, and actually makes shifting *easier* like splatter suggests above. Big improvement when I went from 22 lb. to 11 lb. flywheel in my 240Z
That said, I probably wouldnt' bother unless there was work going on in the trans/clutch area anyway...