I am making a sprite based game for the iPod and am adding colliders to my object. The objects are all flat so the z-depth will not affect collisions. Since most of the the colliders are box colliders, I was wondering if I should make the z-depth a tiny number like .1 or just 1. My reasoning is that a depth of .1 would lead to a smaller area to calculate ,or a depth of 1 would lead to quick calculations because inputing 1 in math is easier than a decimal. These are just guesses keep in mind.

What I am asking is which reasoning if either would actually be a better a optimization.