MOUNTAIN VIEW, CA — Firefox 3, which launched just before noon PDT on Tuesday, cleared more than 8.3 million downloads in the first 24 hours it was available online, according to Mozilla.org, the developer. That makes it a candidate for the Guinness Book of World Records.And that’s despite periodic server outages caused by massive consumer demand.

Mozilla is waiting for the Guinness folks to say “yea” or “nay” before making any official world-record announcement, but unofficially the developer said Firefox 3 download rates peaked at 14,000 per minute on Tuesday and were hovering around 6,000 per minute early Wednesday.

How many of the downloads were by users who actually will employ the new browser version is unknown. Pundits speculate that most Firefox users will replace their second-generation versions of the world’s second-most-popular Web browser with the shiny new software, but Firefox 3 won’t take any significant bites out of the overwhelming dominance enjoyed by Microsoft’s Internet Explorer. Market research firm Net Applications recently pegged Firefox 2 at an 18-percent market share and Firefox 3 at 4 percent in the span of 24 hours. Apple’s Safari browser trails in third place in the browser wars.

“…[T]he fact that Mozilla’s Download Day drew as much attention as it did indicates that Firefox is more than just a piece of software,” CNet’s Stephen Shankland wrote in his blog. “It’s a movement people want to belong to.”

Reviewers have waxed ecstatic in the cybersphere.

“Firefox 3 is poised to usher in a new phase of Web browsing that will change how Web applications are built and delivered, and even how most of us use and think of the Web,” eWeek’s Jim Rapoza gushed at the Ziff Davis-owned site. Firefox 3 “may make it possible to finally deliver on the old promise of the Web as operating system.”

In active development for nearly three years, Firefox 3 focuses on security. The underlying engine, Gecko 1.9, has undergone more than 15,000 updates since the previous Firefox version was released, including some aimed at improving performance, stability, rendering and code sustainability.

Particularly exciting about the new Firefox is a built-in malware-protection system that warns users when they arrive at sites known to harbor viruses, spyware, trojans and other nasties. Forgery Protection blocks the content on sites suspected of containing forged material. (Can you say “phishing?”) The browser also automatically disables old and insecure add-ons and plug-in versions.

Many reviewers like Firefox 3’s ability to save usernames and passwords after a successful login, instead of before the login has been completed. (That’s a major gripe for many users. Poorly executed keystrokes have caused incorrect passwords to be stored for more than one hapless cybercitizen.)

The new browser integrates with Web-based email providers so users have an easier time using their favorite apps to correspond with website administrators via email links embedded in their sites. Downloading and bookmark saving and sorting have been simplified and made more intuitive.