At its peak, Firefox's Web site was serving 17,000 copies a minute. Downloads came from some 200 countries, led by the United States, Germany, Japan, Spain and Britain.
Firefox supporters were seeking to set a world record for most software downloads in a 24-hour period. The category is new, and Guinness World Records must certify it, a process that could take a week or longer.
The free software continues to be available, but downloads won't count toward the potential record.
Tuesday's release was delayed more than an hour as visitors checking for the update overloaded Firefox's Web servers. The site was slow or unreachable for about two hours starting about 12:45 p.m. Eastern time, 15 minutes before the scheduled release time, according to AlertSite, an Internet performance monitoring company.
Firefox comes from Mozilla, an open-source community in which thousands of people, mostly volunteers, collectively develop free products. Firefox is the No. 2 Web browser behind Microsoft Corp.'s Internet Explorer.
Firefox 3 includes enhancements to help users organize their frequently visited Web sites and block access to sites known to distribute viruses and other malicious software.
Users of Yahoo Inc.'s mail service can also use Firefox 3 to send e-mail by clicking a "mailto" link they might come across clicking on a name or a "contact us" link on a Web page. Previously such links could only open a standalone, desktop e-mail program.
Firefox 3 also offers other design and speed improvements.
