Are you a user of the popular Firefox web browser? After 12 betas, 2 release candidates, and over 8 months since the first public beta, the final version of Firefox 4.0 is finally released.
There are too many new features to go over all of them, so here is a first look at what I think are the best new features of Firefox 4.0.
Performance and Speed
One of the most important aspects of the web browser these days is performance and speed. Firefox 4 promises a significant improvement in speed especially with Mozilla’s new Jägermonkey Javascript engine.

Mozilla's Speed Comparison between Firefox 3.6 and Firefox 4.0
Firefox 4.0 also includes support for graphics hardware acceleration to give certain graphics intensive tasks to the GPU. Unlike the recently released Internet Explorer 9, this works on Windows XP. Firefox also takes advantage of Direct2D and Direct3D on Windows and OpenGL on Mac.
Streamlined Interface
Following the footsteps of other browsers, Firefox 4.0 introduces a streamlined interface with a unified Firefox menu button, top tabs, combined stop and reload button, and a missing status bar.

Firefox 4 Interface
Like almost all other browsers, tabs are now found above the location bar. When Firefox is maximized, it uses the same row as the menu button. Otherwise, it’s on a second line so there’s room to drag the window around.

Firefox Tab Bar when maximized with 2 tabs and Gmail running in a Pinned App Tab
Tab Management
Are you opening too many tabs? A feature introduced in Beta 4 is Panorama Tab Grouping. It allows you to create tab groups to help organize your tabs as well as stay focused. The concept is similar to virtual desktops.

Firefox Tab Grouping
Can’t find the tab you need? You can also search your open tabs from the location bar.

Switch tabs from the Location Bar
Sync – Same Experience Everywhere
Firefox 4.0 integrates Firefox Sync (formerly Weave) which syncs your bookmarks, passwords, history, and preferences online so they can be accessed anywhere. This allows your Firefox experience to be the same everywhere including on mobile devices like Android and Firefox Home for iOS.

Firefox Sync Options
I’m sticking with Xmarks and LastPass though as I use multiple browsers on multiple computers and Firefox Sync only supports Firefox.
Add-on Management, Auto-Update, and Restartless
With Firefox 4.0, manging add-ons no longer takes place in a separate window, but a new tab instead.

Firefox 4 Add-on Management
By default, add-ons now update automatically without any user interaction. Updates are automatically installed when the browser restarts. This can be disabled in the settings menu of the new add-on manager.
In an attempt to follow the footsteps of other browsers, certain add-ons no longer require a browser restart. These add-ons are tagged with restartless. However, unlike other browsers, Firefox add-ons can do much more therefore some add-ons probably won’t be able to activate without a restart.
Firefox 4.0 took a very long to be released with an original expected release date of late 2010. Mozilla intends on changing their release cycle by following Google’s footsteps: more frequent releases and less new features in each release. In fact, Mozilla intends on releasing Firefox 7 in 2011, which is a huge change considering its been almost 3 years since Firefox 3.0.
So what are your thoughts about this new release of Firefox? What’s your favorite feature? Share your thoughts in the comments.