Designed on Flash 8, problems with 9 player

I have recently created a little game, just a cheapy little one but fun none the less. It runs great local running in the 8 stand-alone player but seems to slow to a crawl when played in the browser with the 9 plugin. I am using the drawing API and bitmap caching, do you know if they re-did those for flash player 9 and it has a hard time running them or what the heck is goin on?

EDIT: While in browser, proccesses stay low and changing the quality has no effect on performance.

Many thanks guys,