Out of curiousity, would you be able to lop off, say, a 2" limb with one of those larger saws by swinging the saw at it (fast enough that the limb couldn't get out of the way, if trees could do that sort of thing ) and pop through it with no noticeable delay in the swing the way you could with, say, an axe?
No.
With a sharp chain, though, and a fast saw,close.