On the heels of Internet Explorer 8 Beta 1, released by Microsoft the past week following the keynote address at MIX08, Mozilla has made available the fourth beta of Firefox 3.0. Just like IE8 Beta 1, Firefox 3.0 Beta 4 has a strong focus on developers, with Mozilla stressing the fact that the build is designed for testing purposes only, and not for general use. But just think of Beta 4 as yet another step on the Firefox 3.0 beta saga. An epic that has reached its 12th chapter after four Beta and 8 Alpha development milestones. At this point in time, Mozilla is already hard at work planning its next step, namely Firefox 3.0 Beta 5.

"New features and changes in this milestone that require feedback include 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 recency 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," stated Mike Beltzner, Mozilla user experience lead.

According to Beltzner, Mozilla has also tweaked the performance of the browser. Users should experience what Mozilla referred to as a drastic cutdown on the amount of memory used in prolonged sessions. Beltzner also pointed to modifications in the JavaScript engine, synonymous with increased speed when it comes down to web applications. Looking ahead, Mozilla plans the code freeze for Firefox 3.0 Beta 5 on March 18, and in this context, with a traditional baking time of approximately one week, the next Beta for the open source browser could drop by the end of the month.

Firefox 3.0 Beta 4 for Windows can be downloaded from here.
Firefox 3.0 Beta 4 for Linux is here.
Firefox 3.0 Beta 4 for Mac can be grabbed via this link.