Firefox 11 is Smaller and Faster

We quietly shipped Firefox 11 with a bunch of performance fixes that both reduce the amount of memory that Firefox uses, and improve the responsiveness of it’s user interface.

These types of changes are not easy to talk about. Often they’re very technical, and meaningless to anyone but the developers involved, which is probably why we usually don’t enumerate them in the the release notes or other public announcements. “Firefox is 74% faster when you open menu X, and twice as fast in some garbage collection scenarios!” Yeah, not an eye-popping headline. We could do a lot better in communicating these improvements in broadly meaningful ways though – nice graphs or some competitive site like arewefastyet would help a lot. But until then, here’s a short summary of the improvements in Firefox 11. And if you know of other performance fixes that don’t fall into the categories below, please add them in the comments!

Memory Use (aka “memshrink”)

The Memshrink project has been going for quite a while now, led by Nicholas Nethercote. He blogs weekly updates on the project’s activity. According to Bugzilla, there were 29 memshrink bugs marked fixed during the Firefox 11 development cycle – four of which were P1, or very high priority. Some of the fixes were related to tools and detection methods, but many are actual reductions in memory use. The changes that made it into Firefox 11 include fixes for detected leaks, removing of zombie compartments, lazy-loading data, reducing the size of some caches, reducing memory used while scrolling, and many more.

UI Responsiveness (aka “snappy”)

The Snappy project started last December, and is run by Taras Glek. Its aim is to improve the responsiveness of the Firefox UI. Taras has been posting weekly updates on Snappy activity on his blog. Bugzilla shows 15 snappy bugs marked fixed during the Firefox 11 development cycle. The project had just started, but there are still some significant wins in this release! Firefox 11 includes reductions in queries in the bookmarks system, reduced preference lookups, faster data collection for session restore, and various improvements in the DOM code.

Add-on Compatibility

While it’s not related to performance, I do want to call attention to something that many people don’t seem to know: In Firefox 10 (yes, the previous release) we stopped marking most add-ons incompatible when you upgrade. That means that a LOT more of your add-ons will continue to work when you upgrade Firefox from here on out. The only add-ons that still require compatibility bumps are those that have binary components, since they need to be recompiled against the current version.

Download Firefox 11.

12 Comments on “Firefox 11 is Smaller and Faster”

  1. Kwjor says:

    Say, whatever happened to Chrome-style process separation, i.e. with different processes for different tabs? Is that still on the table?

  2. […] latest version of the Firefox browser hit the web this week and it’s quite an impressive update. The theme for version 11 of Firefox was “lighter and faster”, continuing a march forward on […]

  3. Kwjor – that was shelved in November or December, as it was a very long-term project which required significant resource investment, promised to break the vast majority of existing addons, and did not promise equivalently extraordinary gains in responsiveness, etc. We decided to invest the engineering efforts required in working on a number of other projects that promised much more tangible and quantifiable responsiveness benefits in a much quicker timeframe. Project Snappy is the result of that decision.

  4. Nigelle says:

    Add-on Compatibility
    “we stopped marking most add-ons incompatible when you upgrade. That means that a LOT more of your add-ons will continue to work when you upgrade Firefox from here on out. The only add-ons that still require compatibility bumps are those that have binary components, since they need to be recompiled against the current version.”

    In most of the cases this help users but this has also created new cases of crashes see :
    [Bug 731692] Obsolete dictionaries seems to crash Thunderbird but cannot be erased.
    Some non compatible extensions have been inactivated by releases previous 10 and so caused no problems but now they are re-activated and may crash FF…
    Add-ons that have still an high compatibility limit too low (e.g. < 8 or 9 or 10) should also require compatibility bumps.

    The present extension manager works well only with extensions installed by the user in one of his profiles. If they are more or less system wide it is difficult to UN-install them and clean each profile : this occurs in particular with old dictionaries.

    To be user friendly, extension manager should deal (install+delete) correctly with the system-wide or at least user-wide (if the access rights are too difficult to manage) extensions for dictionaries and very commonly used extensions (as "is it compatible, etc.) and avoid to install a dozen times the same extension…

  5. Nigelle says:

    At each release FF is said to be faster by Mozilla and it is true because most individual processes need less time.
    At each release FF seems slower to the users and it is true because if you double the number of individual processes each needing 3/4 of the previous time, you have a total time of 1.5…

    This is provocative but partly true due to the inflation of new features…

  6. […] Com sempre, es recomana a tothom actualitzar-se, no només per les noves funcions que porta, sinó perquè també representa una millora de la seguretat (corregeix  5 vulnerabilitats crítiques i 3 de moderades) i del rendiment (aquí hi ha més informació). […]

  7. joey says:

    One of the biggest problems I’ve got with Firefox is its poor integration with OS X. For example : drag’n’drop an image to the desktop. Yeah it’s not where you dropped it. If you put it on the side of the Dock like most people do, you might not even figure out that the icon is behind the window. So you try it again, until you look at the desktop and drag’n’drop then move the icon where it was supposed to be.
    So you might lose something like 5-10 seconds per drag’n’drop to the desktop. About what you gain with super-optimisations after viewing 200 pages or so.

    Google made some user tests with the native dropdowns, too. The OS X one was by far the fastest to use amongst all systems. But hey, you know what ? OS X users can benefit the real original Windows 2000 look’n’feel of dropboxes thanks to Mozilla.

    These are just two example but I have plenty of similar problems that make Firefox a far less productive tool to use than, well… Safari, of course, which is the only browser I know to have so much polish for every feature.
    Just try the “Find in page” command (Cmd+F) on Firefox and Safari : one is perfect, displaying the number of occurrences, with a very neat highlighting. It appears with a little animation to be sure that you notice where it is.
    The other one has a terrible color scheme in every ways, highlights all as an option, shows up at the least visible place and places the next button at the left, which is the opposite of the arrows to move from page to page in the browser history. Well, it’s just wrong and it didn’t evolve for years and years.

    This is so sad. I used to love Firefox, now I wish I could but I just can’t anymore.
    Please, fix the mess Mozilla.

  8. Nigelle says:

    Faster or snappy ?
    I remember some releases that were catastrophic due to knew functions as indexing in the background. Can you give a list of features that slow FF when running on ? So we can make FF faster by setting them off if we don’t absolutely need them…

  9. […] Firefox 11 is Smaller and Faster « […]

  10. Andy says:

    “we stopped marking most add-ons incompatible when you upgrade.”


    Frankly, this was the most annoying thing in _all_ Firefox 3.x-9.x. (or was it even starting with 2.x?) Can’t remember. Anyways, you simply *can’t* expect add-on developers to always “upgrade” their add-ons just by releasing “new versions”, which in effect does not mean anything but releasing the very same code with a modified install.rdf.
    Obviously this has annoyed many developers; and users too, who simply hacked the .xpi archives so that they work with newer versions. (Normally they always did work.)

    Wait…I think I’ve just heard you say “Hack XPI? You know that you can install a toolset which will let you install ‘incompatible’ add-ons as well”.
    ‘course you can. But contrary to most users’ belief, the error messages about incompatiblity will NOT go away, but in an ugly fashion stay present and even disturb the view in the add-on manager. So the only sane way out for FF <= 9.x was to HACK the xpi and really physically bump up the version number.

  11. Filippos says:

    Yeah!!! That’s true! Firefox is faster on my laptop and my smartphone which supports Android OS! I think that very good job was done on the perfomance parts! Plus, Firefox has greater variety of plugins!

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