[eluser]Mirage[/eluser]
I don't think that multiple view calls (same as includes) are overly expensive with today's filesystem performance. However, I'd find it a bit overkill to do it at that fine grain.
Along the lines of what xwero said, build up you hierarchy in an array, load the menu view template and loop over it. If the menu hierarchy is somewhat static, you could also put it in a config rather than generating it.
HTH