Mozilla releases Firefox 9, claims to boost JavaScript preformance by 30%

Does it feel like you just updated to Firefox 8? That is because you literally did just update to Firefox 8. But hey, Mozilla has a rapid release cycle schedule to meet. Who cares if these rapid updates are bloody annoying. Here comes Firefox 9.

Firefox 9 doesn’t contain as many user-facing changes as previous updates. Rather, most of FF9 changes are under-the-hood, aiming to make up for Firefox’s recently bloated past:

  • Added Type Inference, significantly improving JavaScript performance
  • Improved theme integration for Mac OS X Lion
  • Added two finger swipe navigation for Mac OS X Lion
  • Added support for querying Do Not Track status via JavaScript
  • Added support for font-stretch
  • Improved support for text-overflow
  • Improved standards support for HTML5, MathML, and CSS
  • Fixed several stability issues

The biggest change in FF9 is undoubtedly the new Type Inference:

Firefox 9 features the release of Type Inference, or TI, a research project under way for over a year. TI is a feature in the SpiderMonkey Javascript engine which generates type information about Javascript programs through a combination of analyzing the program’s code and monitoring the types of values as the program executes. This type information is used during JIT compilation to generate more efficient code; Firefox 9 includes modifications to the JaegerMonkey JIT compiler to use inferred type information. This compilation mode, which is the default in Firefox 9, speeds up major benchmarks like Kraken and V8 by over 30%, and gives a large speed boost to many JS heavy websites.

Now that we know why Mozilla insisted on releasing Firefox 9, let’s hope we don’t break anything (particularly add-ons) while upgrading.

Firefox 9 is going to be rolled out through Firefox’s auto-update starting December 20, 2011. If you are impatient, you can manually update by downloading FF9 from Mozilla’s FTP repository.

Official Mozilla Firefox 9 FTP Repository

[via Ghacks]

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  1. jayesstee

    @Ashraf: This my first post in the last couple of months, comprising of more than three lines, which has not been held for moderation! I’ll stick with the “whole dot thing with URLs” to give my convoluted posts a sporting chance.
    P.S. When I opened my mailbox – eleven (11!) notifications from dotTech. dotTech is buzzing just like old times. :=D

  2. Darcy

    @smaragdus: Here, here, I agree completely. worse is I discovered too late that Firefox’s automatic Add-On updater will update your system to not compatible add-ons. Several of my favorite Add-ons stopped working after an update and I had to update to version 4 to get them back. Some of them I still haven’t gotten back.

    Do you know if the add-ons work in SeaMonkey? I’d switch myself if they do.

  3. Ashraf
    Author/Mr. Boss

    @J.L.: A lot of my issues with FF aren’t the changes they have made but rather the stability, in general, of the browser. I remember clearly FF3.x was great for me. FF4+ I have had regular crashes. FF8 has been the best update in the recent past — made the browser a lot more stable. Hopefully FF9 will continue that.

  4. Ashraf
    Author/Mr. Boss

    @Farrukh: No problem! For what it is worth, FF9 is available via auto-update now — I just did it myself.

    @hatman: I plan on writing the “how to” later today.

    @Grantwhy: Mobile browser machine you are :-P

    @Grantwhy: Ah that is interesting. I didn’t know the updates are instant on portable versions too, now. Do you know when they made that change?

    @smaragdus: FF3.x was the best FF version. Ever. Period. I remember FF4+ has just been downhill.

    @Jimmy: You are welcome!

    @Zapped Sparky: Re: no Firefox anger management class for me tonight — LMAO!

    @Fred: Yeah, easily. Just turn on Returnil’s disk protection before upgrading and ensure in settings Returnil is set to drop all changes upon reboot.

    @Rick C.: Interesting. Thanks for that tip.

    @ebony: Did you miss the dT article on Gushpippy? :-P

    @ebony: FF3.x is good but you must almost note later versions of FF have security updates. So, yeah.

    @Jeanjean: You are welcome — and thanks for keeping me informed about that issue!

    @Jason Carver: Meh. With larger and larger HDDs I find installing multiple browsers a non-issue.

    @jayesstee: Your directions are spot on — my article will say much of that, expect with addition of a few tweaks.

    @jayesstee: Oooo good add-on there.

    And why is everyone doing the whole dot thing with URLs? LMAO if you are only posting one URL you are good to go. Spam filter only goes berserk if you post multiple URLs or style your comment a lot.

    @hatman: Try the latest — v9.

  5. J.L.

    A fanatic post with dinosaur mentality.

    – Do numbers really matter to users? Talk about caring for pointless things.

    – What a hyperbole, and completely ignorant. RSS icon isn’t an important feature, more like extra add-on functionality. Also the add-on bar is far more customizable than the old status (you can add any button to it).

    – Get a theme then, it’s identity is dependent on the user.

    – about:config fixes that, Firefox is made for the masses, which can be idiotic.

    – Your machine or brain’s issue, all valid data proves the exact opposite.

    I can elaborate as well. There are replacement add-ons, Add-on Compatibility Reporter, etc. so don’t be lazy.

  6. Joseph Londe


    Use the PortableApps (from version of Firefox on any HDD, USB drive or SD card. It’s self standing and won’t install as a Windows program as such, so you can remove it by simply deleting the directory (i.e. no rubbish left in registry), however, you can’t run it simultaneously with another version of FF.

  7. hatman


    Than you for taking the time to post those instruction. Very appreciated. I have 3.6.3. I will install various version between 4 up to 9 so I can experience the Changes. Thanks for the links. That extension sounds good and I will also get MozBackup.

    What versions should I try? I was thinking 4,5,6,7,8,9

  8. jayesstee

    As a regular idiot, I recommend that you try the following:
    1. Create a new folder called anything other than plain “Firefox”. “Firefox 9” would be good.
    2. Do not let Firefox update itself. Download the version 9 to manually install it.
    3. Do not let Firefox install itself. Take control of the installation by selecting the “custom”, NOT “standard” installation. This allows you to choose your newly created folder to install this version of Firefox.
    4. When installed, create a new desktop icon pointing to the “Firefox.exe” in the “Firefox 9” folder. Give it the name “Firefox 9” or anything other than “Firefox”.
    You should now have two versions of Firefox.
    Go play and compare and perhaps report back whether you think FF 9 is better or worse?

    @Anyone who has upgraded Firefox and regrets it:
    Previous versions of Firefox can be found at: kb dot mozillazine dot org/Go_back_to_an_old_version_of_Firefox
    I would recommend using “MozBackup” to save settings, favorites, history etc before deleting the later version and installing the earlier version of FF.
    MozBackup can be found at: mozbackup dot jasnapaka dot com/

    @Anyone who has upgraded Firefox and has trouble with Add-ons:
    I have found the FF extension “Add-on Compatibility Reporter” is magic. After installing, add-ons that FF reject as not compatible start working. Well worth a try!

  9. Jason Carver

    I usually pick one browser and stick with it, because it just clutters the disk space. Google Chrome really works good for me. The only reason I use another browser in case a site does not work on another.

  10. Jeanjean

    @ Ashraf for information:
    Since you go back over Firefox, I profit to communicate what I have does to resolve my problem (disappeared colors and disorderly posts) with this browser.
    Since a reinstallation over the old version did not change anything, I’ve made a backup of my profile & data with “FavBackup” (
    Then I’ve complety desinstall Firefox and reinstall it.
    When I’ve restore my profile – and then only – I received a message saying that 3 or 4 of my extensions were not compatible with Firefox 8.
    Since then… no problem anymore!
    Best regards.

  11. Fred

    Would it be possible to use a program such as Returnil System Safe Free to install and test Firefox 9 then once you re-boot you would hopefully lose all the changes made during the install and revert completely back to your older version of Firefox?

    Has anyone tried this with Windows XP SP3 already?

  12. Zapped Sparky

    Does it feel like you just updated to Firefox 8? Nope,because I didn’t :) I’ve had terrible problems with the even numbered Firefox’s, so I been waiting for the odd numbered to come along (why I have no problem with them I have no idea). What problems are those you ask? I’d rather not think about it, ta very much :)

    Ah go on then, install failure, crashes on opening, corrupted profile, missing profile (thank you backup), it’s persistence in forgetting what my passwords are (thank you encrypted backup), bookmarks vanishing, add-ons becoming incompatible and finally nagging me that there’s an update available to X.X.1 within days of just updating to X.X.0.

    I feel much better getting that out, no Firefox anger management class for me tonight :)

    On the plus side it has got faster and uses less memory, so, er, yeah, it’s alright.

  13. Jimmy

    Thank you Ashraf for another grate article

    @ Those that wish to test an app…

    To test the latest version of any app, I run a virtual OS in VMware Workstation, then use (Portable_App_Creator_0_97_3_beta) to make a portable version. That works for me.
    To find out where to download Portable_App_Creator_0_97_3_beta use Google search
    Hope this helps

  14. smaragdus

    The guys from Mozilla ruined the best browser ever with version 4 so I was forced to switch to SeaMonkey (which uses the same great Gecko engine but allows more customization and the GUi is not ruined).

    Firefox has been crippled in every possible way since version 4 (the beginning of Firefox downfall):

    – preposterous version numbering- it is absurd to release buggy versions without thorough testing, it is absurd to try to catch up with Google Chrome version numbers, it is absurd to torture add-on developers- most of them develop add-ons in their free time so they cannot keep to this crazy release contest with Google Chrome and as a result many add-ons turn out to be incompatible with every new Firefox version.

    – removal of everything useful, for example- RSS icon from the URL bar. The classic Status Bar has been removed and replaced with the terrible add-ons bar (the +(close) button is just idiotic, the visible bars could be customized from Options menu). So users are given no options to customize the browser. Firefox developers (Asa Dotzler and the like) are deaf to users’ opinions, suggestions and feedback and it seems that their target group is not the power users but the ignorant masses (an example of their absurd logic- only 10% of Firefox users use RSS feeds, so then let’s remove it entirely from the URL bar with no option of enabling it, which will have only one effect- those who has been utilizing it will suffer while those who have never been aware of what RSS means will most likely not notice the difference at all).

    – imitating other browsers’ GUIs- copycatting from Opera and Google Chrome will not make those who prefer Opera and Google Chrome like Firefox and switch to it. On the contrary, those who have been using Firefox for years will be disappointed since one of the reasons of choosing Firefox has been its GUI. As a result of the GUI change Firefox lost its identity.

    – removal by default of http:// – this is sheer idiocy since it prevents users from copying/sharing/saving/publishing the exact URL address of a web page.

    – with every new release Firefox becomes more and more resource-hungry, less stable and slower.

    I can elaborate more on Firefox collapse but I don’t have the time. In brief- Firefox looks like Opera/Google Chrome now but performs much worse- it starts slower, loads pages slower, crashes often, it has been stripped of functionality and customization options, with every new release there is a large number of add-ons that would not work being incompatible, and has adopted a ludicrous version numbering (for less than a year the version number doubled- for 7 years of development Firefox has reached version 3.6+ and for 9 months it accumulated to 9/10) that does not illustrate the actual development.

    Before version 4 I recommended Firefox to everyone and installed it to my friends’ machines. I do this no more.

  15. Grantwhy


    With the more recent portableapps Firefox Portable releases, you can use Firefox’s internal updater instead of waiting for them to build a updated release so once Firefox release 9.0 you could try updating Firefox Portable that way.

    From memory they (portableapps) (apparently) fixed/worked around the problem with the internal updater – although it would be a very wise thing to make a backup copy of your Firefox Portable before you do so.

  16. Grantwhy


    I agree with Jacal. If you really want to test different/newer versions of Firefox try a portable version (from

    their main Firefox page:

    for older/different versions: (scroll down the page)
    or try their FirefoxPortable SourceForge page:

    please be aware that newer versions of Firefox are also Security Updates, and running older versions will make you less secure.

    I currently use a portable version of FF8 as my main web browser, and also have FF 3.6.24 installed on the same USB memory stick^. They run fine from a hard drive and don’t interfere with a ‘regular’ installation of Firefox – although you shouldn’t install portable programs in the Windows “Programs” folder. Windows apparently does odd things to portable programs when they are installed in the “Programs” folder.

    ^heh – I also have portable versions of Google Chrome, Iron, Opera and Maxthon on that USB memory stick, just for the fun of it (and a little bit of looking at/trying other browsers + as backup if a site doesn’t like Firefox)

  17. Ashraf
    Author/Mr. Boss

    @Jacal: I was thinking the same thing. Issue with portable versions is they have an update delay.

    I think I figured out how to install multiple versions of Firefox on the same computer so I will probably publish an article on that tomorrow.

  18. Ashraf
    Author/Mr. Boss

    @hatman: Hmm… that’s an interesting topic. If I figure out how I may post an How To.

    @foolofgrace: You need to shrink an existing partition to create unallocated space.

    @hatman: I would think installing them into different folders would work but I’m not sure.

    @Farrukh: WAS. It’s 20th where you live; not where Mozilla lives :-) Plus that file hasn’t been updated since 12/19/2011 10:17:00 AM.

    I’m certain give it a few hours and Mozilla was announce it, probably early morning 20th. Regardless, though the installers are of the final version in that FTP link. If they weren’t final, they wouldn’t be there. They would be in 9.0b folder.

  19. foolofgrace

    maybe install ff on a separate partition? Dunno. I was just trying to make a simple partition on my laptop hdd the other day thru the Windows 7 interface but my screen didn’t match the instructions, I couldn’t find any “unallocated space” to click on. Ideas welcome.

  20. hatman

    Thanks Ashraf. I use Firefox 3.6.3. Works good for me. I use an extension called Gishpuppy that allows me to create anonymous e-mail addresses. Does not work past 3.6.3.

    I’m trying to figure out how to run multiple Firefox versions so I can test them. Someone tried to explain to me before but the tech guys always use the Geek lingo that I don’t understand. Totally messed up my Firefox and could not revert to what I had to before. Firefox usually will not change back even if system restore point was set. Messing up my Firefox browser can make hours of work for me to reset up.