I just switched off to "Chromium" at the recommendation of Flaw3d and CCarter. It's cool and apparently it's what Chrome is based off of, but it doesn't include all of Googles bullshit.
I use FF, I don't really care about RAM, since it's pretty much free nowadays, but since last update or so FF somehow started to randomly delete my browsing history, and that's just retarded, so I'm considering switching to something else.
Be careful if you use Excel 2010 and run Chrome at the same time. There is some weird bug that fucks the copy and paste function - you can't paste formulae.
The only thing I miss from Firefox is the lack of a way to get side tabs in Chrome. I still use both though. I find Firefox handles >50 tabs much better than Chrome does.