The release of Firefox 3.5 came as the open source browser is proving an increasingly formidable challenger to Microsoft's Internet Explorer 8, which once had over 90 percent market share.
In June, Firefox has a 22.5 percent market share according to web metrics company Net Applications, behind Internet Explorer's 65.5 percent. Though Internet Explorer's share has been declining for some time, the slide has accelerated over the last year since Firefox released version 3.0.
Mozilla, the organization that distributes the open source browser, said the new version is twice as fast as the previous version, and also includes a "private browsing" feature, also called "porn mode," that allows users to hide their tracks when the option is turned on.
Other privacy options allow users to easily and selectively wipe their web history.
Mozilla claimed a world record for software downloads when the previous version was released a year ago. The organization said that even more users were downloading the new browser.
