On my notebook with 2GB and Windows XP, Firefox 3.5.2 uses about 150MB of the memory with 4 tabs open. Is there a way to reduce the amount of memory that Firefox consumes?


This works wonders!

  • Check your Extensions and Themes. (By running Firefox in safe mode.)
  • Check the Plug-ins.
  • Clear Download History.
  • Restart Firefox Periodically.
  • Assign Memory Cache on Firefox. (browser.cache.memory.enable and browser.cache.memory.capacity)
  • Release Memory when Firefox is minimized. (config.trim_on_minimize)

150mb isn't that much of memory usage. However, there are plenty of tweaks in about:config - here's a guide at http://howto.helpero.com/howto/Reduce-Firefox-Memory-Usage_4.html.

Edit Unfortunately, it appears that the link is being fiddled with by SU's markdown.

  • 1
    Your linkie is broken. – TheTXI Aug 18 '09 at 18:25
  • Silly markdown. It was mucking about with the final underscore. Thanks for the heads up. – EvilChookie Aug 18 '09 at 18:35

I've been testing this for a few days and am very impressed. Reduced from average 150MB to 60MB


Of course, it's an extension so has its own footprint!

  • Thank you so much for this! After soooo long, Firefox is fast again =8-) – Yuval Sep 7 '09 at 12:13

In recent versions, default history setting is 90 days. This causes your Places database's size to skyrocket and can slow down Firefox considerably. Reduce your history size to something more suited to your needs.


Not to self-promote (I apologize), FireTune is a great little tool which can speed up your Firefox experience along with optimizing the memory usage of Firefox.

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    Self-promotion is alright (to a point) as long as your answers are relevant and helpful! – The How-To Geek Aug 18 '09 at 19:51

One thing that has worked well for me is to be very selective with which extensions I have installed (or at least enabled). If I find that I'm not using an extension very often, I'll disable it until I need it.


One of the biggest memory consumers in firefox is flash. If you can't disable the flash completely, try installing Adblock Plus. This will remove at least the flash ads (as long as the other ads)

And btw, 150MB is not that much at all.

  • You can try FlashBlock (don't have the URL handy) which blocks all flash until you tell it to run the flash video. – mrdenny Aug 19 '09 at 3:59

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