I switched to Firefox years ago and never looked back. However, as much as I like it its slowness as of late is becoming very frustrating. With every update and major release the memory leak still remains. Though, I can't blame it all on the browser as I usually have at least two windows containing 4 to 6 tabs open at a time. This will definitely slow things down especially on my laptop which isn't anything special. Still 500MB of my ram is ridiculous. So what does one do in this situation? Search Google for an answer of course. Here is what I found:
For Ubuntu and other Linux distros:
http://www.ubuntugeek.com/speed-up-firefox-web-browser.html
For Windows: The above Ubuntu article should work for Windows as well though I haven't tried it on a Windows machine. You can also use
SpeedyFox . Just download, install, and click the "Speed Up My FireFox" button after opening the program. It worked quite well for me though I had to run it every few days.
I've recently switched to Ubuntu on my laptop and used the first article above and it seems to be working well so far.