Mozilla unleashes Firefox 3 Beta 4

Mozilla accelerated toward the final release of Firefox 3 Monday by posting the fourth beta for download and immediately confirming that it would give developers just a week before it froze the code on the next.

Mike Beltzner, Mozilla's interface designer, touted several improvements that debuted in Beta 4, including full-page zoom, offline data storage for Web apps, and a revamped download manager. The browser's performance has also been boosted, said Beltzner and more of its irksome memory leaks have been plugged.

"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," said Beltzner in a post to the Mozilla developer centers. "Web applications like Google [Gmail] and Zoho Office run much faster, and continued improvements to memory usage drastically reduce the amount of memory consumed over long browsing sessions."

Reducing Firefox's memory consumption has become one of the hallmarks of Version 3's development. The browser, which has been blasted for tying up increasing amounts of memory the longer it's open, now uses an automated cycle collector to free any unused memory and a new allocator to reduce memory fragmentation. Mozilla has estimated that it's plugged "hundreds" of leaks so far.

Updated release notes also published Monday boasted that Beta 4 contains more than 900 enhancements since the mid-February Beta 3, including very visible changes to the browser's look and feel. It is now more in line with the appearance of native applications on the various operating systems on which it runs, said Mozilla.

But as the open source developer unveiled the newest beta, it also confirmed that it would freeze code for the next build, Beta 5, on Tuesday, March 18. Last week, Mozilla's executives, including Mike Schroepfer, the company's chief engineer, decided that there were too many bugs remaining in Beta 4 to move from it to release candidate stage, and announced that a fifth preview would be necessary.

Firefox 3 Beta 4 can be downloaded for Windows, Mac OS X, and Linux in 36 languages from Mozilla's site. However, as he has done in the past, Beltzner again warned casual users to steer clear. "We do not recommend that anyone other than developers and testers download the Firefox 3 Beta 4 milestone release," he said. "It is intended for testing purposes only."

To some extent, Beltzner's advice has gone unheeded. According to Web metrics vendor Net Applications, Firefox 3's share of the browser usage market nearly doubled in February over the previous month.

Mozilla has not committed to a release date for a final of Firefox 3, but based on earlier major upgrades, it's unlikely to unveil the finished product before April.

Computerworld is an InfoWorld affiliate.