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How to Stop a Firefox Memory Leak

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Burnin firefoxFirefox is our browser of choice. It’s fast, stable, and developer friendly. It has tons of useful plugins and themes (skins) you can use to customize and make Firefox your own. The only problem is that amidst the excitement of adding all these cool plugins, you won’t realize the incredible amount of memory that Firefox will begin sucking from your system. The result? Slower loading web pages, a slower PC, slower everything. Fortunately, there’s a couple of steps you can take to get Firefox back on the fast track.

Steps to Halt A Firefox Memory Leak

There are some basic steps you can take to help reduce memory leakage in Firefox. These are:

  • Upgrade Firefox. Newer versions of Firefox use less memory by containing memory leaks more efficiently.
  • Disable unnecessary plugins and add-ons, and extensions (open your “Add-Ons manager” and shut down any you think you don’t need. You can always re-enable them if it turns out you do). This is by far the biggest memory saver. If Firefox is your primary browser, you might also consider using another browser for the add-ons you only use occasionally (for example, Java).
  • Reduce misuse by malicious sites by running a spam or antivirus blocker on a regular basis. We recommend the free Spybot Search & Destroy to get you started.
  • Keep your number of open tabs and windows to a minimum.
  • Type “about:config” in your browser bar and adjust the following preferences (by double clicking on them) to free up some additional memory:
    • browser.cache.memory.capacity (set to 0)
    • browser.cache.memory.enable (set to false)
    • browser.sessionhistory.max_total_viewers (set to 0)
    • browser.tabs.animate (disable)
    • browser.sessionstore.max_concurrent_tabs (set to 0)
  • Here some more advanced settings to speed up page loading:
    • (set to true)
    • javascript.options.jit.content (set to true)
    • content.notify.backoffcount (set to 5)
    • network.dns.disableIPv6 (set to true)
    • network.http.pipelining (set to true)
    • network.http.proxy.pipelining (set to true)
    • network.http.pipelining.maxrequests (set to 8 )
    • plugin.expose_full_path (set to true)
    • ui.submenuDelay (set to 0)
  • When installing extensions, you can kill the default countdown (delay) by setting the following value:
    • security.dialog_enable_delay (set to 0)
  • If you have antivirus installed (Windows only), you can disable Firefox’s native virus scanner:
    • (set to false)
  • Consider installing the Ramback extension (Firefox 3.x+).
  • Windows O/S tips: Turn on virtual memory or increase the size of your paging file.

Also note that the more powerful your computer, the more memory Firefox will use. Benchmarking your Firefox memory compared to other PC’s based on the number of Windows or tabs you have open will be biased based on the power of any particular PC. Bottom line – if you’re able to browse without too much slow down or crashing, you’re probably fine.

Have a Fix of Your Own?

Tried something yourself that significantly increased Firefox memory efficiency? Please share with our readers below. Conversely, if you are having a heck of a time getting Firefox to run alongside your other apps, post below with specifics, including add-ons you have installed, the version of Firefox you’re running, etc., and we’ll do our best to help you diagnose your specific problem.

Alex bring a series of in-depth articles on search marketing and content management systems as well as troubleshooting tips to We Rock Your Web's collection. He is an avid tennis player, nature enthusiast, and hiker, and enjoys spending time with his wife, friends, and dogs, Bella and Lily.

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16 Comments on "How to Stop a Firefox Memory Leak"

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Ram Leakage FIXED!!!!
open C:
go to Windows then click System32 now on your keyboard Shift+Del then Enter

Phil Dansford
Phil Dansford

I switched to Pale Moon, a fork of Firefox before they destroyed the interface. Solved the CPU problem, and I no longer need a bunch of plugins to “put back” the original interface, missing menu options, etc. I was also able to import all my settings, history, and bookmarks with one copy command.

Word Smith
Word Smith

Unless you have some compelling reason to use Firefox as your browser, the easiest fix is to switch to Opera, where you’ll see the absurd number of ads being blocked from Facebook, etc.

I’ve been a Mozilla user for decades, but my needs are simple, and Opera is an elegant, lightweight browser that avoids the RAM glut.

Washington Indacochea Delgado
Washington Indacochea Delgado

Thanks Alex, very useful.


This is outdated as some features not there. New version?

The Ceej
The Ceej
Actually, your first step contradicted itself. Upgrade Firefox, of course. Upgrade to the older version. Firefox 3.6 was the most stable and user friendly, and the last true release. After that they switched to “rapid release” which is just codeword for, “Every version is so shitty, we have to get the next one out as soon as possible.” Newer versions leak like a White House press agent. And please try to remember that “upGRADE” means switch to a better version. So, the case of Firefox (and most Corporate software, actually), and upDATE is a downGRADE, and a downDATE is an… Read more »
Michelle Chan
Michelle Chan

I tried just about everything. I hated to let it go but I had to uninstall Firefox. Nothing I tried worked. I replaced it with UC Browser for PC and I couldn’t be happier.

Open “about:memory” and click the ‘GC’ button to perform garbage collection. This usually resolves the issue, and I’m honestly confused as to why Firefox never performs this automatically, considering it’s built-in, really fast, and seems reliable. I’ve been using Firefox on Windows since version 2, and I have never noticed it perform GC on its own. I just always saw its memory footprint rising and rising with continued use, until at some point (after 2.5+GB memory usage) it would crash. I don’t think I’ve ever witnessed Firefox memory usage go down at all, until I discovered the GC button. I… Read more »

This didn’t do anything for me at all. I have a huge memory leak, sometimes up to 800 mb. I REALLY don’t want to switch to a different browser. The configs in this article are also nonexistent as of 5.1.0, it seems. I’m so lost. I have at least 3 memory leaks of this size that I’m trying to contain, two of them being Adobe’s fault.


That’s the most helpful Firefox Trick I’ve ever read and I’ve been using Firefox ever since version 2. Thank you so much for sharing this!

Gilligan Ragusa
Gilligan Ragusa

GC button! EXCELLENT! I had no clue it even existed! Thank you most sincerely, friend.

KR Rayberry
KR Rayberry

Nice article, thanks. Looks like they may have gotten rid of ‘’. Couldn’t find it on FF 40.

Goey Jann
Goey Jann

Delete it. Fix it.


Type “about:config” in your browser bar and adjust the following preferences to free up some additional memory:




Adjust them to what? how?


You say that older versions of FF use less memory, may be that’s true, but i used 5th version and 4th one and I can say that the earlier version worked better. Besides, the updates of the browser are released faster than the add-ons updates, so i just have to use an earlier version. But I’ll try the extension you recommended, hope it will reduce memory use at least to 500Mb…



Jessy from google android development services


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