Reduce CPU/memory usage of Firefox


Firefox is the best browser around right now, with a large open-source community behind it. Firefox maybe the best in terms of features and flexibility, but all of this comes at a price. Firefox is a resource hog. Firefox 3 has been a lot better at managing resources, yet it has high memory usage, and occasionally, CPU usage hit 100% and the system hangs. It can take up 140 MB of RAM when multiple tabs are open.

There are many reasons for Firefox hanging and/or using excessive memory. Plugins and extensions, which are not part of the default Firefox install may cause this. Poorly optimized sites which load several images and ads may cause this. These are inevitable.

Before mentioning the tips, let me say that upgrading to Firefox 3 is absolutely essential. Firefox 2 was notorious for poor resource and memory management, and Firefox 3 has improved in that aspect a lot. The tips mentioned here are for Firefox 3 (but will work for Firefox 2 too).

  1. Disable Java:
    Disable the Java plugin, by going to Tools>Options>Content tab> uncheck Enable Java. Most sites do not use Java. So, you end up wasting CPU resources for a plugin(yes, it is sorta plugin) that you do not use.
  2. Update Flash:
    Visit Adobe Flash page and update Flash to the latest version. This helps you to get any performance improvements/bug fixes for the Firefox plugin for Flash, which can often reduce a lot of problems.
  3. Flashblock:
    If updating Flash plugin does not help, install Flashblock extension. You will see a play button instead of the Flash content. When you want to play something, click the play button.
  4. Disable problematic extensions:
    Cut down on the number of extensions used. More specifically, try to remove those extensions which access internet to update information for each site(Alexa toolbar, PR tools, StumbleUpon toolbar etc.). This is because such extensions often hang up Firefox while they look up the information online.


    Also, refer to this list of problematic extensions.

The fact is, these little things can be the difference between a crashing browser and a perfectly-working one.


  1. i am not being funny, i’ve been using ff 2 for a while to see what’s new and as soon as i open 15+ tabs the cpu usage shoots up to 90% – which makes everytinh else very very slow. It might be a glitch, but i don’t seem to be alone…

    So I will again stick with Opera – and i am not flamewaring here. [i keep opera open in background all the time with around 20-30 tabs open]
    Opera is not for everyone i guess, but is THE army-swiss-knife of web-browsers for those who prefer productivity and ergonomics; while Firefox is what IE desperately wants to be, a web-browser for everyone, simple to use, fully expansible tool.

  2. I agree. And I have NO extensions installed and am still having the 100% CPU usage issue with 3 tabs open (news, blogs, nothing exotic), even after adding a gig of RAM.

    I’m going back to IE until this gets addressed.

  3. @Deepak: I agree with the images thing. It should be done only if you’re on a slow system (remember, there are plenty of users still stuck on P4 computers). As for Java, I still recommend it, because Java is not used very frequently now.

    Opera is built to be light weight, and FF was so until v1.6. Mozilla claims so because it caches most pages and images previously visited (link). I’ve updated the post to reflect this info.

  4. I back Alfred. I feel it’s just not worth surfing without images and java plugin, if you surf sites other than news and feeds, in which case the content is all that matters.

    Opera doesn’t have the multiple tab hog like Firefox does. Funnily enough, Mozilla says the resource hogging is a “feature”. 😀

  5. @Alfred: Java plugin is not used enough to justify the resource consumption, so I disable it. Again, its upto you – I personally like everything light and responsive rather than heavy and feature-ladden. Also, it all depends on the PC config you have. Besides, I said it about disabling images when you have 20+ tabs each with 15+ images, which adds up to quite a handful.

  6. Sry but removing the java plugin and images… its just not worth surfing like that..
    but cutting down on the extensions would definately help

  7. @Shankar: Thanks. And yes, avoiding less used extensions is good, but I recommend removing those which access the web for info, like PR tools/Alexa toolbar.

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