The web world is abuzz today with the release of Firefox 3.5. On the launch page, Mozilla touts the results of running SunSpider. Over on UA Profiler, I’ve developed a different set of tests that count the number of critical performance features browsers do, or don’t, have. Currently, there are 11 traits that are measured. Firefox 3.5 scores higher than any other browser with 10 out of 11 of the performance features browsers need to create a fast user experience.

Firefox 3.5 is a significant improvement over Firefox 3.0, climbing from 7/11 to 10/11 of these performance traits. Among the major browsers, Firefox 3.5 is followed by Chrome 2 (9/11), Safari 4 (8/11), IE 8 (7/11), and Opera 10 (6/11). Unfortunately, IE 6 and 7 have only 4 out of these 11 performance features, a sad state of affairs for today’s web developers and users.

The performance traits measured by UA Profiler include number of connections per hostname, maximum number of connections, parallel loading of scripts and stylesheets, proper caching of resources including redirects, the LINK PREFETCH attribute, and support for data: URLs. When I started UA Profiler, none of the browsers were scoring very high. But there’s great progress in the last year. It’s time to raise the bar! I plan on adding more tests to UA Profiler this summer, and hope the browser development teams will continue to rise to the challenge in an effort to make the Web a faster place for all of us.