Booting from such a flash drive does take awhile, but I have no good answer to the format time. Did you do a low level format? sounds like it. Takes a long time for a 16gb flash drive to zero.
I also stumbled across a way to boot snow leopard on a flash drive, on a pc, now that's an interesting trick. Also extremely slow to boot. (7-10 min)
So it's not just the mac, it's the flash.
You could always go with a kanguru firewire flash drive. Too bad those are (still) sickeningly expensive and very low capacity. I don't understand why this is.
