Mozilla last Friday shipped the beta of Firefox 5, the latest step in its move to pick up the release pace of its open-source browser.
Firefox 5 is slated to wrap up on June 21.
The company's developers merged the changes made over the last several weeks in Firefox 5's less-polished "Aurora" channel to the beta on May 17, as planned.
It takes Mozilla time -- in the case of Firefox 5's beta, three days -- to run automated quality control tests and prepare distribution mechanisms after merging the code, the company noted earlier this month.
As befits the more frequent release schedule that Mozilla staked out last month , Firefox 5 sports relatively few major changes.
The two that Mozilla called out in a blog post Friday were support for the CSS (cascading style sheets) animation standard -- which has yet to win formal approval from the W3C (World Wide Web Consortium) standards group -- and the inclusion of a "channel switcher" that lets users flip between Firefox's three editions of Aurora, Beta and Release.
Google's Chrome and Apple's Safari already support CSS animations.
Firefox 5 contains many more under-the-hood changes than Mozilla called out, however. The company listed 1,053 stability and other fixes in the detailed release notes accompanying the preview.
Firefox 5's user interface is identical to its predecessor, Firefox 4, which launched two months ago.
Under the new Firefox development regime, Mozilla engineers will add features as they're completed, rather than hold them while all work on the next upgrade is completed. If a feature presents problems during testing -- say in the Aurora channel -- it will be yanked, then re-inserted into a later cycle after fixes have been applied.
Like Google, which upgrades Chrome about every eight weeks, Mozilla will trade more releases for fewer new features and visible changes in each edition.
Mozilla may have denied copying Chrome's upbeat schedule, but analysts have noted the similarities and pointed out the need of all browser makers to step up the pace to keep up with the increased competition.
Most have done just that.
For example, Microsoft debuted Internet Explorer 9 (IE9) in mid-March, then almost immediately issued a developer's preview of IE10 , hinting that its browser releases are on an annual schedule, more than twice as fast as previously. And earlier this month, Opera Software launched what it called "Opera Next," a separate development build of its browser that is updated much more frequently.
"Competition always makes people move faster," said Jan Standal, Opera's vice president of desktop software.
Opera upgrades its browser about every two months.
If Mozilla meets its intended deadlines, Firefox 6 will ship on Aug. 9, six weeks after Firefox 5. New editions are to reach users at six-week intervals after that, meaning that Mozilla will have wrapped up Firefox 9 by the end of 2011, assuming its developers don't take time off for the holidays.
Firefox 5 Beta will be automatically offered to users who have previously installed a beta of Firefox 4. Others can download the preview for Windows, Mac OS X or Linux from Mozilla's site.