i agree that, most of the time, if you want to convey speed you shouldn't use slow motion. that's why Jackie Chan's best fights don't have any slow motion. you get to see how fast his kicks and punches are because they look as fast as lightning...not because they take 5 seconds to land.
slow motion should be use for graceful, beautiful flying sequences, impact shots (Superman throwing a real time punch, then slowing down the shot right after the punch lands), or suspense moments (slow motion shot of a woman falling then speeding up again to real time with Superman catching her just before she hits the ground).
if you have to show that he's faster than a bullet, don't do it the way Singer did by having the bullets in slow motion and Superman flying past them at regular speed. have the bullets move in real time and show Superman as a blur, almost as if he teleports.