Mozilla is in the process of pushing Firefox 9 out to users on its release channel, about six weeks after the release of Firefox 8. The major stated improvement to Firefox 9 is what Mozilla calls the Type Inference for JavaScript, which it says improves performance up to 30 percent in some benchmarks. To test this, I ran a few quick SunSpider tests to compare performance to older versions of Firefox and current versions of Chrome and Safari. These tests were run on a 2010 iMac running OS X 10.7.2 with all updates installed and are only meant to measure relative performance between browsers running on the same computer.

Update: We've also run Kraken 1.1 and the v8 Benchmark Suite version 6 on the same browsers - these numbers come a bit closer to realizing the 30 percent improvement over version 8, while even more conclusively demonstrating how far Firefox has come since version 3.6.

SunSpider 0.9.1 JavaScript Performance

v8 Benchmark Suite, Version 6

Kraken JavaScript Benchmark 1.1

In a standard SunSpider run, Firefox 9 is consistently faster than Firefox 8, but not by anywhere near 30 percent (bearing in mind, of course, that this is just one synthetic benchmark among many). Also note that JavaScript numbers are just one facet of performance - while Safari edges out Firefox 9, to me it seemed a bit slower than both Firefox and Chrome when launching and loading pages. All current browsers completely wipe the floor with Firefox 3.6, both in JavaScript numbers and in apparent speed, so whatever you use you're going to be browsing much faster than you could at the beginning of the year. Increased competition has clearly been good for the browser market.

Firefox 9 also brings two-finger navigation to users running OS X Lion - swiping left on a multitouch device will go back, and swiping right will go forward. Safari and Chrome have already implemented this feature, and while the functionality is the same in Firefox, those browsers include visual cues (arrows in Chrome, a visual sliding of the page in Safari) to let you know that you're doing it, visual feedback that I find helpful. There's still no support for fullscreen mode, though plugins exist to give this functionality to those who want it.

The rest of the improvements can be found in the usual laundry list of small security and bug fixes (including one I had run into where attachments wouldn't download properly when using the Outlook Web App - useful information for shops running an Exchange server). You can get the new browser by using Firefox's built-in updater or by visiting

Note: At the moment, Mozilla says that it's not pushing Firefox 9 out to OS X and Linux users automatically because of "a possible issue affecting a small number of users." We'll keep an eye on this and update the post as events progress.

Source: Mozilla

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  • anonymous_user - Wednesday, December 21, 2011 - link

    Maybe they're having compatibility problems with an older add-on. Or maybe they find updating so frequently annoying.
  • ET - Thursday, December 22, 2011 - link

    I don't think there are more releases than there were in the Firefox 3 era. They are just numbered differently. And the update process is so streamlined I have no problem with it. It downloads automatically in the background, and all I need is a restart, and after a quick install my browser is back up to where it was.
  • tipoo - Wednesday, December 21, 2011 - link

    I'd like to see these two in future benchmarks. Opera has stayed competitive in every feild, its not the "best" at anything but its good at everything, almost as fast as Chrome, almost as customizable as Firefox. Apart from the odd 1 in 100 site it has quirks with it keeps me happy.

    And Palemoon is Firefoxs source code recompiled to use newer instruction sets like SSE2, providing a speedup instead of maintaining compatibility with processors no one on this site uses anymore like Firefox does. It also has stable 64 bit releases of Firefox, and it seems to work fine with every extension. If you use FF, no reason not to use Palemoon, IMO.
  • Andrew.a.cunningham - Wednesday, December 21, 2011 - link

    I think in the future I'll switch to a Windows test box so I can also put IE numbers up there, too. I started out wanting a quick set of numbers and it got away from me a bit. :-)
  • tipoo - Wednesday, December 21, 2011 - link

    Ah, I guess my eyes skipped that paragraph and went straight to the benchmarks. I wonder if the performance change is different under Windows? Time for an end of year Anandtech browser roundup, me thinks :)
  • Arnulf - Wednesday, December 21, 2011 - link

    Wow, they are at 4.0.9 already ?
  • Hrel - Wednesday, December 21, 2011 - link

    I am extremely annoyed by these updates. I am not updating to 9. Every single time NONE of my add ons work. I have to go searching for ALL of them a couple weeks later. Main updates instead of incremental = worste idea ever.
  • jramskov - Thursday, December 22, 2011 - link

    You must be using some odd and lousy coded add-ons since Mozilla automatically tests all add-ons (hosted at Mozilla) and the large majority works without a problem and will therefore automatically be marked as compatible with the latest release.

    Firefox was my primary browser for a long time but then I switched to Chrome. Since Firefox 7 though, I slowly started using Firefox more and these days it is my primary browser.
  • Penti - Friday, December 23, 2011 - link

    It's seriously not worse then the 0.1 releases before when it comes to add ons it's even better most of the time.
  • gorash - Wednesday, December 21, 2011 - link

    Awesome, the sunspider is 0.009 sec faster than the previous version.

    Are these even meaningful anymore?

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