Firefox uses too much memory (RAM) - How to fix

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  • Creator: michro
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Firefox sometimes uses more memory (RAM) than it should. This can make Firefox slower, and in extreme cases, it can even make Firefox crash.

Memory use by any program is affected by many factors, such as memory leaks, conflicting third party programs, and usage patterns. This article describes how to make Firefox use less memory.


Extensions and themes

Extensions and themes can cause Firefox to use more memory than it normally would.

To determine if an extension or theme is causing Firefox to use too much memory, start Firefox in its Troubleshoot Firefox issues using Safe Mode and observing its memory usage. In Safe Mode, extensions and themes are disabled, so if you notice a significant improvement, you can try disabling or uninstalling extensions.


Plugins to display special types of content can consume large amounts of memory, especially older versions.

You can test to see whether one of your plugins is causing Firefox to use too much memory by selectively disabling some of them:

  1. At the top of the Firefox windowOn the menu bar, click the Tools menu, and select Add-ons. The Add-ons menu will appear.
  2. Select on the Plugins panel.
  3. Click on a plugin in the list to select it, then press Disable to disable it.
  4. Repeat for some of the plugins in your list.

After disabling some of your plugins, close and restart Firefox, and observe its memory usage. If you don't see an improvement, you can enable those plugins again and try with a different set.

If you do see an improvement in Firefox's memory usage after disabling a certain plugin, you may leave it disabled or try to see if there is an update for it. Use plugins to play audio, video, games and more lists several plugins and how to install the latest version of each.

Restarting Firefox

Firefox's memory usage may increase if it's left open for long periods of time. A workaround for this is to periodically restart Firefox. You can configure Firefox to save your tabs and windows so that when you start it again, you can start where you left off. See Restore previous session - Configure when Firefox shows your most recent tabs and windows for details.

Using fewer tabs

Each tab requires Firefox to store a web page in memory. If you frequently have more than 100 tabs open, consider using a more lightweight mechanism to keep track of pages to read and things to do, such as:

Memory troubleshooting tools

Firefox developers have written two extensions to help users isolate leak bugs:

  • Leak Monitor : Can alert you immediately when certain types of leaks occur. This makes it easier to figure out what triggers these leaks.
  • RAMBack: Lets you flush many of Firefox's caches, allowing you to distinguish caching from leaking.

If you're a C++ programmer, you can even try your hand at some of the tools Firefox developers use to debug leaks.

Based on information from Reducing memory usage - Firefox (mozillaZine KB)