This tip below may be worth a try to speed things up a bit, but not sure if it would affect start up. It's from a blog where some guys are testing out FCPX on a 9 day bike race, shooting mixed formats and editing for broadcast. Definitely worth checking out. I think they ended up with about 5400 clips.
" I just found a simple way to speed things up: Menu "View-> Hide Waveforms", do that for the Event and you can race through the icons even faster.....WOW! In the timeline it also helps to turn them off or just change the clipappearance in the bottom right."
http://fcpxmegatest.blogspot.com/