Tips to reduce memory usage on Firefox | Linux

For most users, Firefox doesn’t use an abnormally large amount of memory. For others, however, Firefox’s memory consumption is a major problem (Especilaly for people using old computers with limited memory resources), in same cases memory usage in Firefox is due some to other sources, like number of plug-ins, themes and extensions. Keeping firefox updated is always a good solution, because all newer versions use less memory than the older ones. In this article i will try to show you some tips to use if you want to reduce memory usage on Firefox.

Extensions and themes

Poorly designed or incompatible extensions can cause problems with your browser, including make it crash, slow down page display, etc. If you encounter strange problems relating to parts of the browser no longer working, the browser not starting, windows with strange or distorted appearance, degraded performance, you may be suffering from Extension or Theme trouble. You need to restart the browser in Safe Mode, to do that open the terminal and type one of the commands bellow :

./firefox-bin -safe-mode   or    firefox -safe-mode  (For firefox 3.5 and older)

When started in Safe Mode all extensions are disabled and the Default theme is used. Disable the Extension/Theme that is causing trouble and then start normally.

If you find a significant reduction in memory usage, you may be able to find updates for your extensions and themes or alternative extensions and themes that use less memory. Failing that, uninstalling the extensions and themes is an option.

Check the Plug-ins

Plugins (Like Flash player, Adobe reader, java, …etc) can cause Firefox to use more memory when they’re used and may not release their memory until Firefox is closed. It’s a good idea to make sure you’re using the most recent version of every plugin. To save the maximum amount of memory, uninstall any unnecessary plugins.

Clear Download History

Memory usage can increase and Firefox can slow down or freeze if the download history is allowed to accumulate
a- You need to delete downloads.rdf to clear the download history
b- Go to Edit –> Preferences then click Privacy and uncheck “Remember download history” then close

Restart Firefox periodically in case of Growing memory usage

If you find that Firefox’s memory usage continues to grow after long periods of being open, you may want to consider periodically restarting Firefox to bring the memory usage back to reasonable levels. Close Firefox and select the Save and Quit option to reopen your tabs when Firefox restarts.

Settings to reduce memory usage

By default Firefox uses system memory and doesen`t use memory cache. To reduce memory usage, it is important to assign a fixed memory cache

  • Open firefox browser and type about:config in the address bar.


  • Type browser.cache.memory.enable in the Filter field :

Ensure that is cache is enabled and is set to true, if it is false then double click on false line to set it to true.

Now you have to set the cache value :

1-Right click on the browser

2- Copy browser.cache.memory.capacity to the preference name

3-A new screen will appear where you have to enter the value

Now enter the vlaue of Memory cache in KB.

– 512MB of RAM: Enter 8192 as the value
– 1GB of RAM: Enter 16384 as the value
– 2GB of RAM: Enter 32768 as the value

After finishing restart your Firefox.

Finally, to view current memory cache usage of your firefox, in the address bar type :


Important : ALways keep your Firefox updated, newer versions of Firefox are less memory usage than the older versions.

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