Test Drive Firefox 3.1 Beta 1

Update: I’ve written an updated post about the newest Firefox 3.1 Beta.

Mozilla recently released the first testing version of the next major Firefox release. Not all features planned for Firefox 3.1 are included in Beta 1. You will find: fancy Ctrl-Tab tab switcher, the faster TraceMonkey JavaScript engine (instructions to enable later in this post), location awareness on WiFi networks (demo here), OGG built-in media player (demo here), and tag drag and drop.

With the new JavaScript engine, which rivals or surpasses Google Chrome’s, Firefox 3.1 Beta 1 is faster than ever. This is why I wanted to try it out on Ubuntu, here’s how to install it without disturbing your existing Firefox 3.0 installation.

fancy Ctrl-Tab tab switcher

  1. I have not had any issues with Firefox 3 Beta 1 sharing a profile with Firefox 3, but you should backup your Firefox profile just in case something goes wrong. First you may want to clear Firefox’s cache to make this backup smaller. To do this, open Edit->Preferences->Advanced->Network and click Clear Now. Running this command will backup your profile to firefox_profile_backup in your home folder:

    cp -r ~/.mozilla/firefox/ ~/firefox_profile_backup
  2. This command will download and extract Firefox 3 Beta 1 to a folder named firefox in your home directory. Paste it into a terminal (it’s one line) to run it:

    wget -O - | tar xj -C ~
  3. To run Firefox 3.1 Beta 1, first close any other versions of Firefox. Then run the command below to launch it:


The first time you launch Firefox 3.1 Beta 1 you will be prompted about incompatible extensions and to accept a license agreement. Firefox crashed the first time I ran it before showing the license, but after starting it again Firefox was fine.

You can create a menu item for Firefox using System->Preferences->Main Menu and the previous command.

To get your plugins from Firefox 3 (such as Flash and Java) to work, copy them from /usr/lib/firefox/plugins to ~/firefox/plugins.

Firefox’s fast TraceMonkey JavaScript engine is included, but not turned on by default. Open about:config in Firefox, and click through the “this might void your warranty’ warning. Find the javascript.options.jit.content option using the filter, and change the value to True by double-clicking.

I ran the SunSpider JavaScript Benchmark, here are the results:

Firefox 3.1 Beta 1 with TraceMonkey performed almost twice as fast as Firefox 3.0.3! I’ve especially felt the increase in performance in Gmail and a few other JavaScript-intensive sites I’ve tried.

Archived Comments


Will it be installed by default in 8.10?


in full 9.04, Yes it will.


Hi Tom, great guide, yes the javascript is so quick now! Here are my results for reliability (from the UK)

6557.2 - Firefox 3.03
5075.0 - Firefox 3.1
3075.6 - Firefox 3.1 with TraceMonkey


Say, how’s the performance, does it start faster or is it still a bit slow ?


FF 3.1b1 is beautiful! Fast. Stable. Just all-around one of the best pieces of software I’ve used in 25+ years.

Minor note: my plugins dir is /usr/lib/firefox-addons/plugins. This is on an Ubuntu Hardy system.


Awesome, going to try this out, thanks Tom.


The crtl-tab switcher is not enabled on mine. It just works like 3.0. Do I need to manually enable it?


Nope, Mozilla does many beta releases so Firefox 3.1 won’t be finished for a while yet.

It seems to start in about the same time for me (but I always have Firefox open anyways).

The new tab switcher should be enabled automatically.


It seems that the switcher only is activated if you open more then 2 tabs.



Check browser.ctrlTab.mostRecentlyUsed preference in about:config. It must be set to “true”. The new tab switcher work with 3 or more tabs opened.



This isn’t currently working for me. When Run, I get this error:
/home/User/firefox/firefox-bin: error while loading shared libraries: cannot open shared object file: No such file or directory

Is this because I’m running amd64 version of Hardy? or is this only for intrepid?


Hi all,
good gude!!

I have done the test using chrome and is really fast, better than firefox!!


( I prefer in any case firefox)

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