Once it gets going though it screams. Not sure I want to trade the miniscule difference in startup time for that.
As for page load times, this is silly. There is no startup time on a page at all. Possibly the first hit but there are warm start options for that in CLR at least which make this a complete non issue.
To give you an idea, 98% of our page hits are under 80ms processing time and we have big, heavy pages (we're old school asp.net mostly).