Make Firefox Start Faster On Windows

Martin Brinkmann
Sep 21, 2011
Updated • Mar 8, 2015

Back in January we reported that Mozilla Firefox would get faster startup times on Windows. The patch, proposed when Firefox 4 was still in beta, has been implemented in Firefox 7, which is currently available as a beta version for all supported operating systems.

Without repeating what has already been said, the patch preloads a library basically which can reduce the load time of the browser by up to 50%.

The developer of the patch yesterday complained about how the Windows operating system was making it nearly impossible for Firefox to utilize the faster startup time. He noticed that Windows Prefetch was the culprit. Turned on, it would render the improvements useless especially on slower machines that would otherwise benefit the most from them.

The developer has two suggestions on how to cope with the situation. First to disable prefetch (or the prefetch entry of Firefox) which may not make sense on all machines (SSD users on the other hand should disable prefetch). Second to install Firefox anew and reboot the system before starting the browser for the first time.

Above helps populate the Windows Prefetch in a less counter-productive way. Explanation: on warm startup Windows Prefetch records irrelevant IO operations and blocks Firefox startup to preload files that Firefox accesses after startup.

About 25% of all Windows users who have enabled telemetry data have Windows Prefetch turned off. The remaining 75% therefore may not benefit from faster Firefox 7 startup times because of what the developer discovered and implemented.

It is clear on the other hand that the majority of Firefox users are using the latest stable build which is Firefox 6 at the time of writing. Those users won't benefit from the faster startup times until Firefox 7 final is released. According to schedule, this is going to happen on September 27.

The best option then is to install Firefox 7 directly, and not use the internal updating mechanism to upgrade the browser. That is, unless Prefetch is disabled or another operating system is used.

You can read the complete blog post over at the Mozilla website.


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  1. ilev said on September 22, 2011 at 8:17 am

    How to make Firefox shutdown faster when plugin.container.exe consume 80% cpu for 2 minutes during the shutdown process (on my Firefox 6, XP SP3) ?

    1. Strawberry Sundae said on September 22, 2011 at 12:00 pm

      80% cpu for 2 minutes during shutdown? Wow, I’ve never even heard of that problem.

      You’d probably have better luck finding a solution to a problem like this on a forum that deals with such problems like Mozillazine, than in the comments section of an unrelated news article. You’ll probably be less likely to come across a FUD troll, too.

  2. Jojo said on September 21, 2011 at 8:41 pm

    This is more stupidity from FF development and further justification for cleaning out the whole organization. Prefetch/Superfetch exists for a reason. One shouldn’t have to muck with it to make an application “faster”.

    I like this comment in the blog post:

    on 21 Sep 2011 at 9:47 am Tomas B

    I stop reading your article at the second sentence. That is exactly why firefox is losing its cool. It’s becoming too large for ALL OSes (what other OSes am I not aware of that ff load faster?)

    The Mozilla team like to blame everything on everybody else except their ancient code base. I don’t see the IE9 and Chrome having problem with cold boot and I don’t see them complaining about superfetch (it’s a function of windows for a reason). What I see is IE9 and Chrome solved their boot time and Mozilla complains about it.

  3. Crodol said on September 21, 2011 at 8:05 pm

    Honestly, I am also a bit confused as to what to do…

  4. RUCRAZY said on September 21, 2011 at 6:49 pm

    ‘Prefetch’ is the term the used for WinXP and Vista. In Win7 it is called ‘Superfetch’.

    If you want a faster Firefox, try Palemoon. It is a Windows optimized version of Firefox.

  5. Ricky Stallman said on September 21, 2011 at 4:53 pm

    I can’t say that I’m surprised that Windows slows Firefox down while attempting to “help” it start faster. Maybe I’m too cynical?

  6. Threshold said on September 21, 2011 at 3:54 pm

    I am a bit confused at what I should do.

    I use the Nightly build.
    On Sept. 27 Nightly 10 should come out.
    At that point what should I do to improve startup times?
    Uninstall it, reinstall it, not launch it and reboot?

    Also how do you disable prefetch on a single entry and should I do that too?
    Thanks :)

    1. Martin Brinkmann said on September 21, 2011 at 3:57 pm

      You find the Prefetch folder here: C:\Windows\Prefetch

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