Mozilla Corp. late Monday released the first beta of Firefox 3.0, but continued to warn most users to stick with production Version 2.0.

"We do not recommend that anyone other than developers and testers download the Firefox 3 Beta 1 milestone release," Mike Beltzner, Mozilla's interface designer, said in a note posted to the company's development center. "It is intended for testing purposes only."

But while the official word was for users to stand clear, Beltzner's personal recommendation was a lot less intimidating. "It's a preview release, so use with caution and don't expect your add-ons to work without some magic; but between you and me, I've been running on this 'developer preview' for at least three months, and have never looked back," he said in a post to his own blog.

Beltzner also touted several of the improvements in Firefox 3.0, including new security features and tools, a redesign of the bookmarking and browser history and numerous back-end platform enhancements, but he said they all require more testing and user feedback. The company has posted a more complete list of new features in the release notes it added to its Web site Monday.

On the security side, Firefox 3.0 adds malware check, a phishing filter-like feature that warns users attempting to reach a URL blacklisted for suspected malicious code hosting; one-click site information that displays site ownership; fixes for vulnerabilities in plug-in updating; and integration with antivirus software and Windows Vista's parental control settings.

Mozilla also claimed that it has fixed more than 300 individual memory leaks and added a new cycle collector to eliminate other memory issues. Firefox has a reputation for leaking memory consuming large quantities the longer it's left running, and ultimate slowing down its host computer although some of its developers have contested the claims, and even pegged the problem as one of perception.

Most current Firefox plug-ins Mozilla calls them extensions will not work with Firefox 3.0, a stumbling block for some who might otherwise want to test the preview. "Users of the latest released version of Firefox should not expect their add-ons to work properly with this beta," the beta's release notes read.

Firefox 3.0 Beta 1 can be downloaded for Windows, Mac OS X and Linux in 21 language versions from Mozilla's site.

Mozilla has not set a deadline for delivering the final edition, and apparently does not intend to. "The final version of Firefox 3 will be released when we qualify the product as fully ready for our users," its release notes said. By the timeline it set for itself midyear, Mozilla is more than three months behind schedule, in part because it extended the alpha-testing stage to encompass eight versions.

This summer, Mozilla pegged Beta 1's release for late July with a second beta in September, both to precede a final release by the end of the year. The company is now shooting to deliver a second beta before the end of the year, with more betas possible before producing one or more release candidates in a run-up to final code.

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