I flip between two extremes on the same bike. Most of the time I run 42mm Conti Crossrides, (420 g) but once a year I run an Attack /Force set 24mm rear 22mm front ( 195-175 g) for a month or two.

The only difference is PERCEIVED acceleration and of course the weight, comfort and the ability to go about anywhere without a second thought on the 42's.

There's no real difference in speed on flat pavement!

On the other hand I have run some 32's that were really slow.

it really does come down to tread and case design.