I've always wondered about height zoom

Why is it that when zooming vertically in the track view there is a lag evident. It seems that Sonar is sort of standing at 1 when the user zooms from 1-1.49 and then jumps to 2 when the user gets to 1.51.

Does this have to do with fractions or surds or something because it is curious. Other DAWs are more responsive in this area.