Firefox Consume Too Much Memory Hack

1) Speed up Firefox. If you have a broadband connection (and most of us do), you can use pipelining to speed up your page loads. This allows Firefox to load multiple things on a page at once, instead of one at a time (by default, it’s optimized for dialup connections). Here’s how:
Type “about:config” into the address bar and hit return. Type “network.http” in the filter field, and change the following settings (double-click on them to change them):
Set “network.http.pipelining” to “true”
Set “network.http.proxy.pipelining” to “true”
Set “network.http.pipelining.maxrequests” to a number like 30. This will allow it to make 30 requests at once.
Also, right-click anywhere and select New-> Integer. Name it “nglayout.initialpaint.delay” and set its value to “0″. This value is the amount of time the browser waits before it acts on information it receives.

2) Limit RAM usage. If Firefox takes up too much memory on your computer, you can limit the amount of RAM it is allowed to us. Again, go to about:config, filter “browser.cache” and select “browser.cache.disk.capacity”. It’s set to 50000, but you can lower it, depending on how much memory you have. Try 15000 if you have between 512MB and 1GB ram.

3) Reduce RAM usage further for when Firefox is minimized. This setting will move Firefox to your hard drive when you minimize it, taking up much less memory. And there is no noticeable difference in speed when you restore Firefox, so it’s definitely worth a go. Again, go to about:config, right-click anywhere and select New-> Boolean. Name it “config.trim_on_minimize” and set it to TRUE. You have to restart Firefox for these settings to take effect.

Read Firefox RAM Tips on http://support.mozilla.org/en-US/kb/firefox-uses-too-much-memory-ram