Mozilla is rushing to release Firefox 3.1 but not to sacrifice the quality of the emerging browser. In a post to the Mozilla development forum, Mike Beltzner, the director of Firefox, said that the third beta will added to the development schedule for Firefox 3.1 as one more opportunity for developers to test new features and fix bugs before final release.

Although version 3.1 of the browser is not a major upgrade like previous version it is much anticipated when Google’s Chrome and Microsoft’s Internet Explorer 8 have introduced many advanced features like private browsing (often referred as “porn mode”), memory isolation for tabs as well as improved JavaScript execution and HTML rendering speeds recently.

Firefox 3.1 is expected to feature private browsing mode, thread worker and to integrate “Trace Monkey”, new JavaScript engine whose speed can be comparable to Google’s V8 engine powering Chrome browser. But the enhanced tab switching feature that allows user cycling through open tabs with Ctrl-Tab key combination will be pulled off as result of usability tests showing users didn’t “feel quite right” about it yet.

Mozilla has shipped only Beta 1 six weeks ago, Beta 2 should be available in early December. Schedule for Beta 3 is set in early January 2009 and final release is expected to be ready for download in late Q1 2009, probably before Microsoft begins to distribute official IE8 via Windows Auto Update (if rumors about shipping date of IE8 are correct.)