"If you never open more than five or ten content-heavy websites at the same time, you should never base your browser choice on memory consumption. It simply doesn't matter a lot if your browser consumes 50, 200, or 400 MB of RAM, even on lower-end machines. However, heavy tab multitaskers should steer clear of IE9, Chrome (in all its incarnations), and Opera (Beta). Just go with Firefox. With RAM levels quickly reaching 1 GB with just 15 tabs, you'll encounter sluggishness even on faster machines. Again, it simply doesn't matter if you've got 4, 8, or 16 GB of RAM -- a browser taking up 1 to 1.5 GB of RAM quickly reaches the limits of both the Windows' and its own memory management capabilities. Threads and handles run wild, paging starts kicking in, and overall reliability goes down with responsiveness.
Firefox is the clear winner of the bunch. It was the only browser that did not slow things down and I recommended it for both lower-end mobile devices and high-end desktops. "
http://www.itworld.com/software/266362/whats-fastest-browser-maybe-youre-measuring-wrong?page=0,2