Mozilla has released its almost final beta version of Firefox 3 Beta 4 for developers and testers to download and test it. The new FireFox 3 Beta 4 release has added many new features and changes. The most important and obvious change to this version is the browser’s speed. It was tested and the speed is very much faster than Firefox 2 and Internet Explorer 7 (IE7). However, since the version 4 is not fully developed, Mozilla highlighted this release version is purely for testing only.

Besides the improvement of the browser’s speed, other improvements can be seen in Firefox 3 Beta 4 inclusive of:

• Improvements to the user interface: better search support in the Download Manager, ability to zoom entire page or just the text, continuing look and feel improvements on Windows Vista, Windows XP, Mac OS X and Linux.

• Richer personalization through: location bar that uses an algorithm based on site visit recently and frequency (called “frecency”) to provide better matches against your history and bookmarks for URLs and page titles, as well as an adaptive learning algorithm which tunes itself to your browsing habits.

• Improved platform features such as: support for HTML5’s window.postMessage and window.messageEvent, JavaScript 1.8 improvements, and offline data storage for web applications.

• Performance improvements: changes to our JavaScript engine as well as profile guided optimization resulted in significant gains over previous releases in the popular SunSpider test from Apple, web applications like Google Mail and Zoho Office run much faster, and continued improvements to memory usage drastically reduce the amount of memory consumed over long web browsing sessions.

The Firefox 3 Beta 4 can be downloaded from Mozilla.

Update: Firefox 3 Beta 5