One of Firefox 4.0′s big claim to fame is that it runs on any version of Microsoft’s Windows, from Windows XP forward. Microsoft, itself, apparently cannot find the programming talent to make their new IE9 browser handle nearly 50 percent of the Windows installed base.
 
There is a boat load of new features, including a significant JavaScript speed increase. The TraceMonkey JavaScript engine brings screaming fast performance to Firefox 3.6. With JavaScript that’s more than three times as fast as Firefox 3 and 20 percent faster than Firefox 3.5.
 
Firefox 4 brings a lot of speed improvements... the company isn't comparing themselves with the fierce competition, though.
Firefox 4 brings a lot of speed improvements… the company isn’t comparing themselves with the fierce competition, though.
 
The user interface has been completely revamped and streamlined, with the menu bar condensed under a single button. The Add-ons Manager has been upgraded to a full-page interface.
 
For the first time, Firefox will allow users to synchronize their bookmarks across different computers as well as with Android-based mobile phones. This is also the first version of the browser to include the proposed Do Not Track header feature, which can alert Website owners if the user wishes to opt out of third-party Web tracking.
 
There is now Core Animation rendering model for plugins on Mac OS X. Plugins which also support this rendering model can now draw faster and more efficiently. Included is native support for the HD HTML5 WebM video format. On the Acid3 Web standards test, Firefox 4 came in with a score of 97 compared to IE 9′s 95. On the HTML 5 compatibility test, Firefox had a good score of 255 compared to IE’s 130.
 
Another great idea is Panorama. With Panorama you can drag and drop tabs into groups. You can then move them into work, home, or family to easily navigate many open tabs.

Probably the most interesting part from an end user’s perspective is Mozilla’s road map priorities. They plan to ship Firefox 4, 5, 6 and 7 in the 2011 calendar year. This will make it tough for the competition to stay in front of Firefox, but it could make it difficult for Firefox to keep up with their own schedule.
 
The release candidate is available for the Windows, Mac, and Linux platforms, and supports more than 70 languages. A particular plus is that current users of the Beta version will have their browsers automatically updated.
 
BSN* is completing an extensive test comparing the Release Candidate to past Beta versions we have seen. Keep watching here, our results will show up very soon.