I had that problem for a while, but the latest firefox with the latest flash version seem to work fine. Firefox always seems to consume exorbitant amounts of RAM, but I don't mind that.
As long as it keeps running smoothly. With the current versions of things, all seems to be well. I do use Waterfox + Noscript, Adblock and Ghostery though.
1100T, Biostar TA870U3+, 16GB DDR3, 240GB Mushkin Chronos Deluxe, 2x1TB Black, 2x3TB Green, 3GB XFX 7970, Antec 650W, CM690, Dell U2713HM & Samsung 2343BWX