IE8 RC1 gains ground in JavaScript race

The newest version of Internet Explorer 8 is still the slowest big browser when it comes to JavaScript. But it has significantly closed the gap since last summer's second beta, benchmark scores show.

According to tests run by Computerworld , Internet Explorer 8 Release Candidate 1 (IE8 RC1) lags behind its four major competitors in rendering JavaScript -- at times, by large margins.

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Mozilla's Firefox, Google's Chrome, Opera Software's Opera, and Apple's Safari all posted better SunSpider JavaScript benchmark scores, with Chrome leading the pack. It was four times faster than IE8 RC1, while Firefox and Safari were nearly twice as fast.

Computerworld ran the SunSpider suite in Windows XP three times for each browser, then averaged the scores. In SunSpider, smaller numbers are better. The results were: Chrome 2.0.159.0 -- 1275; Firefox 3.0.5 -- 3037; Safari 3.2.1 -- 3050; Opera 9.63 -- 4139; and IE8 RC1 -- 5573.

Although IE8 RC1 was the slowest of the five browsers, its SunSpider score was approximately 70 percent faster than IE8 Beta 2's, which was released in August 2008, and tested by Computerworld last month.

Microsoft, however, continues to dismiss benchmarks like SunSpider. In an interview earlier this week when the company launched IE8 RC1, senior product manager James Pratt criticized such tests. He described them as "micro-benchmarks" that place an emphasis on scores as a "drag race" that Microsoft isn't about to enter.

"We looked at when users load real Web pages," Pratt said, adding that the company tested what he called the "top 25" sites on the Internet. "We looked at where IE spends its time when it shows those pages." Only 20 percent of IE's time is occupied rendering JavaScript, Pratt said. "To say that a browser engine is just a JavaScript [engine] doesn't match the reality of how the Web is built today."

Instead, Microsoft wants to push the discussion toward a more holistic view, and away from just JavaScript. For most users, Pratt continued, it just doesn't matter.

"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. "Beyond building a performance lab, which we've done, it's very difficult to tell which browser is fastest. The reality is that for most users, they'll all be comparable."

Other browser builders would disagree.

Mozilla, for example, has been aggressive in touting its new JavaScript engine, dubbed "TraceMonkey," which it launched last year and has added to Firefox 3.1, an upgrade that has been delayed several times during beta testing.

Computerworld is an InfoWorld affiliate.