Optimization for Flash

I was wondering. . .
Do you guys have any tips for making a flash movie run more smoothly on pretty much any machine (within the standard range). I know when I built a flash site it ran like crap on computers other than mine, but other flash sites that are far more complex run smoothy on just about any machine that I run it on. For instance sixtailer.com. Is it a difference of animating things in frames or making something move or animate using complex action scripting? I figure there is NO difference as the computer still has to render the effects just the same. However I could be wrong. So my question is, is there a way of optimizing flash so it runs really smoothly?

Does it have to do with animating using actionscript vs frames?

Does it have to do with the way a flash file is published?

Answers to these questions plus any tips that you could give me would be a of great help to me and possibly many others who are wondering about this same general concept.

Thanks a lot!