Fixing the Firefox Memory Leak

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Ever notice how surfing sessions with Firefox start out fast and slow to a crawl as Firefox eats more and more memory?  Well, it took a while, but I did.  As we speak, my copy of Firefox is taking up over 270MB of RAM! WTF?  A little research revealed that this is due to a memory leak that was never fixed.  Here's a list of things you can do to minimize the problem:

  1. The first course of action is not a change in settings, rather the first thing you should do is check this list to see if any plugins you have installed are on them.  In my case, I was running the official copy of the Google Toolbar, which has a known memory leak.  This is most likely the true source of my memory problems, not the browser itself.  I was able to uninstall the official Google Toolbar and install the unofficial Googlebar as well as a PageRank addon , to make up for the fact that the unofficial Googlebar doesn't show PageRank.  By the way, I installed these separately instead of using the combined PRGoogleBar because the Googlebar project seems to be more up to day in terms of development.
  2. Start tweaking settings.  By default, browser.sessionhistory.max_total_viewers is set to -1, which means that Firefox will try to determine a good value based on the total amount of RAM you have in your system.  The following table shows what value Firefox will choose based on your total RAM:

    32MB 0
    64MB 1
    128MB 2
    256MB 3
    512MB 5
    1GB 8
    2GB 8
    4GB 8

    I have 512MB of RAM in my Laptop/Tablet PC system, so Firefox would choose a value of 5.  The higher this value is, the more memory Firefox will consume when I use alot of tabs at one, which I do often.  Lowering this value causes less memory to be used but also causes more previously visited pages to have to be re-parsed (thus increasing their load time).  I decided to hardcode this to 2 instead.  A value of 3 may be a better idea, but I want the effects of these changes to be as clear as possible.  By the way, you can access these settings by typing "about:config" into your address bar, without the quotes, and pressing Enter.

  3. There are other values that could be adjusted like browser.cache.memory.capacity and config.trim_on_minimize, but the former already has a pretty small value, and the latter only takes effect while Firefox is minimized, which isn't good enough for me.

Well, that's it.  Good luck.  Be sure to post a comment and let me know how it went.

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