Firefox fans looking for a major update to the open-source Web browser probably will get a final version of it next month.

"We're looking for final ship sometime in June," said Mike Schroepfer, Mozilla's vice president of engineering, in an interview on Wednesday. Mozilla, which was spun out of AOL more than 10 years ago, oversees the Firefox programming project.

One of the Firefox's strengths is the broad collection of add-ons, but that also means things move more slowly when programmers must update their projects to be compatible with Firefox 3. And that's part of what Mozilla is watching closely as it seeks feedback from the 1.5 million people who have installed the Firefox 3 release candidate 1, which Mozilla issued a few days ago.

"We're in a phase where we're letting add-ons get a chance to update," Schroepfer said. "We like to have RCs (release candidates) out for a while to gather feedback."

More release candidates are possible, he said. With Firefox 2, there were three. "We're in better shape this time, but there's no reason to rush this," he said.

The release candidate is available for download for Windows, Mac OS X, and Linux. If you want to try it out, it's best to read the release notes first, in particular the known issues that could trip you up.

After Mozilla's years-long slow start, Firefox has gained significant market share against its top rival, Microsoft's Internet Explorer. Although the latter still dominates the market, Firefox has helped to reignite the browser wars to an extent: Microsoft is investing more resources in IE development, Apple has brought its own Safari to Windows, and Apple and Google are among those devoting attention to the open-source Webkit browser engine project.

Browsers have also become more important as the Internet has begun moving to the more lavish and interactive pages of Web 2.0. For that reason, performance has become a concern: browsers now must execute large amounts of JavaScript code that power-hungry sites such as the office applications of Google Docs and the photo editing of Picnik use.

The Mozilla Foundation has grown significantly over the years. It's set up two subsidiaries, Mozilla Corporation to handle the browser, and the newer Mozilla Messaging group to handle the Thunderbird email software.

Based on market share statistics and the number of Firefox browsers that check Mozilla servers for updates, Schroepfer estimates there are about 175 million Firefox users today.

Firefox crossed the 500 million download mark in February, and now has been downloaded more than 556 million times.

What are Schroepfer's three favorite things about Firefox 3?

• "No 1. is definitely the awesome bar — the smart location bar. It changed the way I use the browser. With a couple keyboard presses, it figures out what page I want to go to." The smart location bar starts suggesting website addresses based on the user's browsing history and can sidestep problems with complicated, hard-to-remember URLs.
• Second is "the performance and memory work. It's 2 to 3 times faster than the previous version and nearly 10 times faster than IE 7," he boasted. "We really tuned the heck out of memory use, so it uses a lot less memory, especially with lots of windows and tabs."
• Third: "The antimalware and security features. We used to tell people not to go to the bad part of the Net. Now we're seeing legitimate sites being taken over," so it's good to have better protection by default.

The CNET review of Firefox 3 RC1 generally concurred with Schroepfer's assessment, though we found the memory improvements were "nothing to write home about," and some performance improvements might be related to the fact that incompatible add-ons weren't running.