On Firefox 4, I have experienced issues running things like Bejeweled Blitz, and Cafe World. When the site loads, it pushes a lot of extra RAM into use simply to load the site, then sporadically freezes as the page is being utilized. When I try to close the tab, it freezes again, and takes 5-10 seconds to get to the point when the tab can simply close. This isn't the case with 3.6.16. It still runs sites running any Flash embed with the same normalcy it had throughout. Firefox 4, however, is a no-go.