The browser upgrade features improvements in performance, compatibility, and speed. A key feature is the TraceMonkey , offering better performance and stability, Mozilla said. The general release is due at the end of this month, depending on whether any bugs are found in the release candidate.

Tools are offered in version 3.5 for controlling private data, including a Private Browsing Model. Support for HTML 5 and elements is featured, including native backing for Ogg Theora-encoded video and Vorbis-encoded video. Also supported are local storage, offline application storage, text, and SVG transforms. Location-aware browsing is included, as is native support for JSON.

The release candidate offered Monday actually is the second release candidate build, but it is the first one directly downloadable form the Mozilla site. The previous build was available to about 800,000 beta users late last week.

A preview release of Firefox 3.5 had been offered early this month.