Why Firefox Takes Up Too Much Memory

According to Mozilla, Firefox is designed to use 100MB to 150MB of RAM. By design, the more RAM that is available on your system, the more Firefox will use. Here are a few things to check if you feel Firefox still takes up too much memory.

Firefox-exe on Task Manager

1. Extensions

Extensions are the main culprit in using too much memory with Firefox. Check under Tools>Add-ons and uninstall any Extensions that you don’t need.

2. Themes/Skins

Certain themes or skins can cause problems with Firefox. Check under Tools > Add-ons and uninstall Themes except for the Firefox default.

3. Certain Web Sites

If a web site has a lot of data in it or something like a Flash movie playing constantly, it will take up a lot of memory. Close unneeded web site tabs or windows that may have this problem.


  1. SaphirJD says

    Never tried Firefox 18, i used very long time Only Beta Versions and have switched now to the Aurora Release Channel.

    Quick, acceptable memory usage even on my EEEBox 1501 from Asus with 2 gb Ram :D

    For all who have lost faith in Firefox, switch to Aurora and enjoy some nice Browsing experience again :D


  2. Rudolph says

    I don’t like Chrome, but Firefox 18 is mostly unusable… right now, 600 MB with 4 tabs opened, that’s ridiculous.

  3. Michael says

    Solved: FireFox eating RAM and crashing. (on Windows 7 ultimate 64 bit)

    After I had endless no. of crashes after update 18 of Firefox I decided to make a clean install. I Found out, that the Adobe Flash Player file:
    could not be deleted, though Flash Player was uninstalled. It seems to be corrupted and has false rights.
    Use the following commands to solve the problem:
    1.) Uninstall Flash Player.
    2.) Open a command box and navigate to the folder and type: regsvr23 /u FlashPlayerPlugin_11_5_502_146.ocx
    Close the box.
    3.) Use Windows Explorer, navigate to the folder again. Right click the file and open security and delete the permission: everyone – deny. Close settings and delete the file and complete folder.
    Now restart.
    Download and install the newest version of Flash Player and Memory of FireFox will remain static.

    Regards from Germany. :-)

  4. Jeff says

    Firefox began using over 1.2 GB of RAM. I uninstalled it, deleted its directories, and then reinstalled, disabling most plugins.

    Same problem.

    Now I’m on Chrome.

  5. nerd says

    There is no single best browser, they all suck in their own way. I’ve settled for Firefox, if it wasn’t as heavyweight as it is then there’s be no grey area on which is best. The best extensions / best security / best ad blocking and a non-profit organisation with an open-source browser is what keeps me using Firefox. Other choices would be SRWare Iron / Opera.

  6. honk says

    HAH 400mb 500mb try 2gigs or 2.5gigs. Open FF and it slowly creeps up from about a 300mb start. Use youtube and itll jump past1gig very quickly. I only have 6gig ram. Onc eit reaches 1.3gigs or so itll start lagging like hell in text boxes and scrolling. I only have ABP and VideoDL helper and agent switcher. Disable all of these uninstall them even running a seprate HDD with a fresh install FF still munches ram. It is a bug in the app none of these farting around with settings will help. FF team just needs to clean up the code vs making things all pretty and more of a PITA to access. 17 has a horrible defocus issue now open links in new window and itll pop behind the previous window once it fully loads. If it was not for the ease of use ABP on FF Id leave for another browser.

  7. TRUTH says

    Firefox sucks. I use multiple browsers. Even opera is getting fat big and slow switching between tabs on my laptop..

  8. JohnC says

    The reason is because when you close firefox, the .exe file does not close. It stays running and continues to use up ram even if you have your setting to delete all history when you close firefox. To resolve, right click your bottom windows tool bar and left click on task manager. Find firefox.exe and end the process. When you restart firefox, the size will be considerably smaller.

  9. Swordshifter49 says

    Fortunately, I have a relatively fast PC so the high memory usage doesn’t phase me too much. However, Windows frequently notifies me that it’s using anywhere from 100 to 400mb, even for one tab. This occurs every. single. time. I open it.

    If it weren’t for Opera’s incompatibility with certain Google services, I’d most likely be using that. Chrome was still the worst experience I’ve had though.

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