Microsoft promises better performance from Internet Explorer 9

Microsoft today claimed that its next browser, Internet Explorer 9, has nearly closed the JavaScript performance gap between itself and rivals made by Mozilla and Google, even though the browser has been in development only a few weeks.

Steven Sinofsky, Microsoft's president of Windows and Windows Live, acknowledged that Microsoft had catching up to do. "We know we have a lot of work to do in some areas of performance," Sinofsky said today at the Professional Developers Conference (PDC).

"On SunSpider, we're on par with IE9," Sinofsky said, showing a chart that displayed scores from the popular JavaScript benchmarking suite. Although IE9's scores were still slightly slower than the newest browsers from competitors, its numbers were significantly better than IE8, Microsoft's current production edition.

"We're getting very close to the other browsers," said Sinofsky.

The news came as no surprise to Asa Dotzler, Mozilla's director of community development, who predicted Tuesday that Microsoft would tout performance gains in its next iteration of IE.

"Microsoft will demo an early build of IE9 that will feature an all new and super fast JavaScript engine," Dotzler said in a blog post yesterday. "Microsoft dug a huge hole when it mostly abandoned IE6 and the web from 2001 until 2006. Their early efforts at ramping back up with IE7 were a big disappointment to most web developers and while their efforts with IE8 were much better, they're still at least a full generation behind the modern browsers."

Microsoft's IE8, and to an even greater extent, IE7 and the older but still widely used IE6, have been left in the dust on JavaScript performance by rivals, particularly Mozilla's Firefox, Google's Chrome and Apple's Safari. The latter two are built atop the open source WebKit rendering engine.

In the most recent SunSpider tests, for example, Chrome raced through the benchmarks about 10 times faster than IE8, while Firefox was nearly four times faster. In the past, Microsoft has pooh-poohed JavaScript benchmarks, calling them nothing more than a "browser drag race" that doesn't accurately portray real world use. Instead, Microsoft has used download tests of the 25 most popular web destinations to claim IE8 is actually faster than Firefox or Chrome where it counts.

Today, Sinofsky seemed to be dumping that stance, and instead bragged not only how much faster IE9 would be, but also that its Acid3 score had improved. "We need to do a better job on Acid3," Sinofsky admitted. "We have made some improvements in IE9, which now scores 32 out of 100." IE8, he said, scored 24 out of a possible 100.

The Acid3 benchmark checks how closely a browser follows certain standards, particularly specifications for web 2.0 applications, as well as standards related to DOM (Document Object Model), CSS2 (Cascading Style Sheets) and SVG (Scalable Vector Graphics).

Other browsers, however, have long been able to max out on the Acid3 test. Current builds of Chrome, Safari and Opera all score 100, while Firefox 3.6, which is still in beta, makes it to 92 out of 100.

Sinofsky did not talk about a release schedule for IE9, or when a public preview would be available, killing rumors that had circulated earlier this week that Microsoft might issue an early build to PDC attendees, saying that the new browser had been in development only for the "last three weeks, since we released Windows 7."

Lacking a released build, it was impossible to confirm Sinofsky's claims of IE9's JavaScript and Acid3 improvements.