Codenamed 'Namoroka' -- the name taken from a national park on the island of Madagascar -- Firefox 3.6 is set to wrap in the next few months as an interim step toward Firefox 3.7, a more substantial update tentatively scheduled for 2010.
As it regularly has in the past, Mozilla warned off most users from trying the alpha. "Please note that this release is intended for developers and testers only," Mozilla said in announcing 3.6's availability.
Firefox 3.6 is based on Gecko 1.9.2, the in-development upgrade to Mozilla's rendering engine.
In an interview last month, Mike Beltzner, the director of Firefox, said Mozilla's internal and volunteer developers were trying to decide whether the follow-on to Firefox 3.5 would be a smaller-sized release that would simply "make 3.5 better," or if it would become a more ambitious upgrade, similar to 3.5's improvements over 2008's Firefox 3.0.
"We're seeing a lot of the competition doing [the former]," Beltzner said, referring to rivals such as Google, which has been aggressively updating Chrome.
Some have criticized Mozilla for falling behind rivals like Chrome and Apple's Safari in speed tests, or playing catch-up to other competitors, such as Internet Explorer, in areas like private browsing, or to Chrome in its ability to "sandbox" each tab.
The debate between making Firefox 3.6 a major upgrade that would involve "wholesale technology change" and "take a fairly long time," said Beltzner, and a minor update that would involve fewer changes and result in a shorter development cycle ended with Mozilla going for the latter. "Namoroka is to be an incremental release, building upon the success of Firefox 3.5," Mozilla said in its Firefox 3.6 public roadmap, which was revised as recently as Saturday.
The schedule that Mozilla has laid out for Firefox 3.6 has the first beta shipping in early September and a second later that month, then a release candidate would available by mid-to-late October. "Aiming at final release for November 2009," Mozilla said in its roadmap.
Among the goals for the upgrade are major performance improvements to browser startup and several common tasks, such as opening new tabs and loading bookmarked pages. Mozilla also wants to customize browser behavior based on the user's past history, add the ability to search for an existing tab and enhance the browser's built-in download manager to support chores like deleting and moving downloaded files.
The Windows version of Firefox 3.6 will also support some Windows 7 features, including "Aero Peek," a new addition to the operating system that lets users look behind any open window to see the desktop.
Firefox 3.6 Alpha 1 can be downloaded for Windows, Mac and Linux from Mozilla's developer centre.