Fifty fish in Microsoft&39's virtual aquarium moved relatively swiftly in this early version of IE9 running with hardware acceleration on Windows Phone 7.

BARCELONA--Apple gets plenty of praise for advancing mobile browsers with its iPhone's version of Safari, but an audience greeted its performance with some laughter as Microsoft compared it to an upcoming version of IE9 for Windows Phone 7.

Joe Belfiore, a Microsoft corporate vice president, showed off the browser here at the Mobile World Congress show during a keynote speech by Chief Executive Steve Ballmer. Specifically, Belfiore showed it running a Microsoft fishtank demonstration that's been in widespread use since the hardware acceleration work began in earnest among personal computer browser makers last year.

And he got a laugh from out of the audience when he compared the 50 fish in the IE9 virtual fishtak on an unnamed HTC phone. They flitted rapidly on IE9 but barely moved on Safari.

"The Safari Web browser is not taking advantage of hardware acceleration so you really get a sense for how dramatic the difference is when we use the full-power capability of the device," he said.

Belfiore neglected to emphasize that the version of IE9 he was pitting against Safari isn't due until toward the end of 2011 with an update to Windows Phone 7, and it's quite likely Safari will look different then, presumably running on new iPhone hardware.

Like IE9 for Windows on PCs, the mobile version includes hardware acceleration in some domains and supports HTML5, a next-generation standard for Web pages. Belfiore also showed the mobile browser using HTML5's ability to show built-in video, in this case with a demonstration version of an IMDb movie site.

Microsoft, lagging Apple's iOS and Google's Android in the smartphone market, is trying furiously to become a contender with Windows Phone 7. Released in November, a minor upgrade is due in weeks bringing copy and paste abilities and some better application performance, said Greg Sullivan, senior product manager for Windows Phone 7. The IE9 for mobile devices will arrive later in 2011 in a major release, an upgrade pace not as rapid as Google's.

Windows Phone customers could well be pleased with IE9--indeed, they'd better be, because it's unlikely they'll get an alternative. That's because Microsoft requires third-party apps to be written in Silverlight or XNA, and browsers today typically aren't.

"If you can write a browser in Silverlight or XNA, you could submit it to the market," Sullivan said. "We have no policy" to specifically bar other browsers, he added.

Opera and Firefox are available on Android, though only in beta thus far, because Google released a native development kit (NDK) that lets programmers write to lower-level interfaces.

Is it possible that Microsoft might take that route Not likely, he said.

"We have no plans" for an NDC, Sullivan said. "We think our development platform and tools are a key strength of the platform."