Flash was designed to load things fast, wasn't it? If it's slow, it's either a) Crapily designed, or b) designed for someone on a T1 connection in which case....it's badly designed!
I agree though, if it doesn't load fully in about 5 seconds, people get grumpy.
I'm still impressed with my little transparent gif or whatever drop-down menues. Royale did a crackin' job on those.