Dramatic Stability Improvements in Firefox

Over the past five months, Firefox has seen a 40% improvement in stability.  That’s incredible!  While the Firefox development community continues to focus its efforts on stability and performance (i.e., 100% improvement is still being strived for), we’re proud to highlight the most recent numbers.

How did we calculate that 40% improvement?  We took a look at the Crash Reports data, along with an estimated ratio of daily crash instances to active daily users of Firefox.  With that data in hand, we first wanted to know how the number of daily crash instances has been trending by major version of Firefox, e.g., is Fx3.6 particularly more stable than previous releases and what does its trending look like?

The chart above looks amazing… and it brought us to the next question… rolling up major versions, what does the total universe of Firefox stability look like?  Using the same numbers as seen above, we simply added them together to come up with the high-level metric – estimated ratio of daily crash instances to active daily users of Firefox.  The trend of the blue line below represents a 40% reduction since early November.  Spectacular!

So, how exactly did this happen?

As mentioned previously, improving Firefox stability was a top level objective of the Mozilla community during the last few months of 2009.  That effort was led by a variety of folks across a wide breath of the community… people who saw the many complaints about crashes, collected the data, figured out what was causing the most pain, addressed those issues (sometimes in code, sometimes by working with partners) and saw product improvements.

And in addition to hitting a home run with Fx3.6 and reducing the crashiness of Fx3.5, a majority of Firefox users quickly migrated to Fx3.6… adding all that up drove what you see in the charts above.

What’s next?

There are still more improvements to come.  For example, with a significant percentage of crashes in Flash, a lot of work around stability improvement for Firefox users is currently going into Flash Player 10.1.  If you’re personally experiencing any crashiness issues when using Firefox, please make sure you’re on the latest version of Firefox and feel free to use tools like bugzilla and hendrix to notify the community.

23 responses

  1. Dan wrote on :

    What are the spikes? (Both up and down)

  2. Daniel wrote on :

    “So, how exactly did this happen?”

    It looks like it happened by having 3.5 being pretty unstable, then improving it to match 3.0. Was 3.0 as unstable in its early life?

  3. AndersH wrote on :

    Why was 3.5 significantly more crashy than 3?

  4. Mike Beltzner wrote on :

    @daniel, @AndersH: a funny thing happened between Firefox 3 and Firefox3.5. We climbed over 20% marketshare, and all of a sudden a bunch of 3rd party software started building on top of Firefox. They were calling deep within our APIs, and when we changed the code in Firefox 3.5, that resulted in crashes. We had taken our eyes of the statistics, and didn’t see this happening early enough.

    Much of the “crashkill” effort was discovering where this was happening, and figuring out how to work with the 3rd party vendors to rectify, as well as to bullet-proof our own code better.

  5. Markus Merz | Hamburg St. Georg wrote on :

    Re. spikes?

    My guess: weekends. More wildly configured + old FF installions than during the week.

  6. john pierce wrote on :

    bull s*** …. 3.5 crashed on me maybe once a month 3.6 crashes on me at least once a day every single day …. 3.6 is by FAR the WORST BROWSER I HAVE EVER USED IN MY LIFE .. opening tabs is now confusing and sucky auto scroll no longer works on a website i visit everyday .. the install was buggy as hell and had to be completely uninstalled and re installed twice so lost the 4 extensions that i use and had to go and re find them and re install

    hey heres an idea mozilla team .. how about working on making firefox the most secure browser on earth like you used to claim and stop worrying so much about adding new features that always end up causing problems and adding bloat and pissing everyone off
    … i long for the days of firebird when it was still a really fast browser

    win7 – 2.7 gig – 6 gig ram

  7. David wrote on :

    Since upgrading I have experienced a number of pages which will not load and for the last 2 iterations a number of slide shows which I have to go to IE to run. No crash but no go, is this stable?

  8. Michael Adams wrote on :

    I love 3.6 (use it at work) & have been using 3.7 builds at home. Regarding those that say they still have problems, maybe a prompt to clear their profile, or an automatic purge of all non-cookie cached data on upgrade/install? (cookies are needed for banking & auto-login sites)

  9. Ron Tilby wrote on :

    According to Mozilla’s own crash stats, Firefox 3.6.3 has a higher crashes per Average Daily User(adu) rate than 3.6.2 or 3.6 See:

    I also wonder if improving crash/adu rates are due to the attrition of users who have experienced a bad crash rate. (perhaps they find a different browser or ‘downgrade’ to an older version of Firefox.

  10. Andy Burns wrote on :

    Does the thunderbird team collect/publish similar crashstats for 2.x and 3.x?

    [err no this isn’t a duplicate comment]

  11. drs wrote on :

    Kinda worthless statistics. It assumes that all users do report consistently regardless of the version and that their total number doesn’t change. If any of that is not true (and it obviously isn’t), then the numbers are complete rubbish.

    Btw, my Firefox crashes like once per 3 months or so. I use it on 3 pc’s, and the number is total.

  12. sam2424 wrote on :

    yet i have def not gotten any crashes recently .. unfortunately dome users are kinda … whats the word … lol

    Serves them right for adding random crap to Firefox.

  13. Gazete Oku wrote on :

    Hi, thank you very much. good job.
    Gazete Oku

  14. A visitor wrote on :

    Just in case, I give some of the most frustrating shortcomings of Firefox 3.6.

    One: symlinked components

    Two: font size and resolution
    Maybe, related to the bugs

    Three: Google hijacked
    One possible fix:

    Four: Javascript downloads an executable to startup directory

  15. Richard Steven Hack wrote on :

    Are you kidding? Firefox 3.6.3 is THE most unstable Firefox I’ve ever used. It crashes several times a day on random Web sites, it can’t handle the full Gmail page AT ALL – and this is AFTER reinstalling with minimal extensions and a new profile.

    It’s garbage. Mozilla’s QA is a joke.

  16. fpiat wrote on :

    I feel the same as Richard. Since about 2 week I get daily crashes, on differents computers. Unfortunately I can’t figure what is going bad and can’t help (:-((.

  17. Russ wrote on :

    agree entirely with john pierce (above). 3.6.3 crashes horribly on several of my computers (windows version) compared to older versions. And, if others’ crashes are like mine, it now dies and doesn’t give an option to submit a crash report (well, one to Microsoft – and I’m sure they’re happy to see these). This is likely why the stats are dropping off (and, that as time goes on people are naturally less likely to submit reports as they figure they’ve already submitted the report and therefore won’t do it again).

    Also agree about the “stop adding features, and get back to a less-bloated, more stable, highly secure browser”… nevertheless, still appreciative of excellent FREE software – don’t confuse my harsh criticism with lack of appreciation for what you guys (and girls) do very well for free.

  18. bob wrote on :

    A horde of Chrome trolls right? 😛

    If you guys FF crash, report (even here too) what happens. But i suspect it doesnt rly crash. It’s honestly very stable. Even minefield rarely crashes.

  19. Mike R wrote on :

    Some of us have given up on crash reports and also have frequent crashes now that take the whole system down. Do those generate crash reports? I also see mostly “This is embarrassing…” messages after crashes now, where in the past Firefox would reopen the pre-crash web pages. This is my first visit here, solely because I have gotten so concerned about Firefox stability. I switched from IE to Firefox because it was supposed to be more secure, more stable, and faster, and I stayed with Firefox for tabs and better password management, but there’s something to be said for being able to view web pages, too.

  20. LinuxChick wrote on :

    Add me to the list of FF crash victims. I now have crashes that bring my whole system down- on a daily basis. I’m glad to see I’m not the only one. This happens in both Linux and Windows BTW.
    Something is very wrong with Firefox 3. I yearn for the old days of Firefox 2. Now that one was stable. FF 3 is now worse than IE.

  21. Greg wrote on :

    3.6.1 has become the worse ever, crashes multiple times a day and seems to always hang on specific javascript functions (like a background AJAX request). I’ve lived with it but soon I will switch to Chrome.

  22. Eng City-Engineering Video wrote on :

    where in the past Firefox would reopen the pre-crash web pages. This is my first visit here, solely because I have gotten so concerned about Firefox stability. I switched from IE to Firefox because it was supposed to be more secure, more stable, and faster

  23. passingby wrote on :

    i am leaving ff for good. simple put, the reasons i left ie are the same reason i am leaving ff. seriously if i have to most or all of my addons as suggested in ff’s support site, why would i want to use FF? i am going with chrome now. 10+ extensions running with “ZERO” crash for a week already. bye bye FF!