To turn on a much faster JavaScript engine and sport a working privacy mode, Mozilla Corp. has launched the first version of its flagship browser - the much-anticipated Firefox 3.1 Beta 2, which can be downloaded for Windows, Mac OS X and Linux from Mozilla's site. The users already running Beta 1 will be notified of the available update in a couple of days.

Beta 2 follows the first beta after an eight weeks' interval, and includes support for "web worker threads" - a developing specification that will let Web-based application developers run background processes to speed up their apps.

Along with incorporating the faster JavaScript engine TraceMonkey as the default setting, and introducing 'Private Browsing', Beta 2 has other improvements as well - the most significant one being the ability to turn off the cache and other private data settings with a single click.

Though Beta 1 had included the new engine, it had been disabled by default; as such, users were required to manually edit the browser's configuration file to turn on the engine. Meanwhile, Private Browsing - the privacy mode that Mozilla planned to add in September - is a reaction to similar additions in other browsers, including Apple Inc.'s Safari, Google Inc.'s Chrome and Microsoft's Internet Explorer 8. It lets users surf without leaving obvious traces of the sites they visit.

In case you want your movements on the Internet should not be recorded, go into 'Tools' on the Menubar and click 'Private Browsing'. Firefox's version of the feature saves all your tabs and closes the browsing session, re-opening a new and empty browser window. The program title bar states that you are using Private Browsing, but there is no blatant icon about the same.