Microsoft: IE8 faster than Firefox, Chrome

"IE8 RC1 is a release candidate, and was very close to being done," explained Pratt when asked why newer versions of Chrome and Firefox had not been used. "But Google and Mozilla were still actively working on [those newer browsers], and they weren't super stable."

JavaScript benchmarks have become a point of dispute between Microsoft and its rivals. While Mozilla, Google, Apple and Opera have all updated their JavaScript engines in the last eight months, and have then trumpeted scores in JavaScript test suites like SunSpider, Microsoft executives have dismissed the bragging as so much noise.

Dean Hachamovitch, IE's general manager, has called claims of competitors a "drag race" that Microsoft isn't interested in joining, while Pratt has downplayed comparisons of any kind. "We're at the point, with what people do in the browser, that users can't really tell the difference between browser [performance]," he said in a January interview.

Pratt said that the just-released report backed that up. "As you can see from the scores, the differences between the browsers are actually very small," he said.

When Computerworld last tested the major browsers' JavaScript performance, immediately after the release of the public beta of Safari 4, IE8 ranked last.

Although Google did not respond to a request for comment on Microsoft's benchmarks, Mozilla's Mike Shaver, who heads all development at the company, applauded any attempt to boost IE's performance. "I don't think anyone here has had a chance to really look at their methodology yet or tried to reproduce their results, but to whatever extent Microsoft is working to improve the performance of IE, it's a good thing for the Web," said Shaver in an e-mail late Thursday.

Microsoft's browser performance report can be downloaded from the company's Web site.