Desktop users, developers, and reviewers all had their download managers aimed at the Firefox Web site Monday to grab Firefox 3 as soon as it launched and also help Mozilla set a world record. World record or not, the latest Firefox release is a world-class Web browser. It looks impressive, renders text and images better than its predecessor, and helps you browse safely. But while it delivers pages faster by cutting down crucial milliseconds, its memory footprint (in unscientific tests) is still as big as a yeti.