You probably have a much better PC. Mine's kind of a POS. :)
I tried switching the quality to low, but that only lasts until the page is refreshed. Next reload, it was back to high again.
And for what it's worth, the slow down was only happening during the actual animation. Once the banner was finished, everything was ok. It would take 10 seconds before that would happen tho, so every page was killing me. FF even hung on me once or twice. :(
It is working beautifully now though with the flashblock add-on.