I've noticed this and I'm wondering whether any of you have noticed the same thing. I'm using Firefox 2.0.0.12. If I visit
http://www.barnesandnoble.com/ , the page has a large area on the upper part of the page which is a scrolling view, moving from right to left, of books. When I'm viewing that page and that area is scrolling, Task Manager (Win XP Pro, 512MB) shows Firefox consuming 95% or more of CPU cycles, causing total CPU usage to jump to 100%. Firefox also tends to lockup; for example, I may not be able to select a different tab or click on any commands on the Firefox menu. The Flash part of that page has a pause button. If I click it to pause the scrolling, then Firefox behaves it's usual self again.
The Barnes & Noble page is the worst case I've experienced, although some other sites with Flash will cause Firefox to spike CPU usage but to a lesser degree. Anybody else ever experienced this?