Firefox 4 regains speed mojo

Beta 7's new JagerMonkey compiler puts Mozilla browser in the No. 2 speed spot behind Opera

With the release of Firefox 4 Beta 7, Mozilla returned to near the top spot in browser performance rankings.

According to tests run by Computerworld, the new browser is about three times faster than the current production version of Firefox in rendering JavaScript, and lags behind only Opera among the top five browser makers.

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On Wednesday Mozilla launched Firefox 4 Beta 7, a preview that includes all the features slated to make it into the final, polished version next year.

Beta 7 was the first to include Mozilla's new JavaScript JIT (Just In Time) compiler, dubbed "JagerMonkey," which shot the browser's performance into the No. 2 slot behind the alpha of Opera 11.

Computerworld ran the SunSpider JavaScript benchmark suite in Windows Vista Business three times for each browser, then averaged the scores.

Three of the five major browsers were closely bunched at the top. Opera 11 Alpha, which the Norwegian company released last month, barely edged Firefox 4 Beta 7, which in turn narrowly beat the beta of Google's Chrome 8.

Meanwhile, results for Apple's Safari and Microsoft's beta of Internet Explorer 9 (IE9) put that pair significantly behind the top three. For example, Firefox 4 Beta 7 was approximately 25 percent faster than IE9 Beta in the trials.

Internet Explorer 8, Microsoft's primary browser, was also tested, although for all intents and purposes, it isn't in the JavaScript race: Firefox 4 was more than 12 times faster at rendering JavaScript than IE8.

Not surprisingly, Mozilla boasted of the speed improvements courtesy of the JagerMonkey compiler, and its integration with the earlier TraceMonkey optimization of the browser's JavaScript engine.

On a company blog telling users to "fasten your seatbelts," Mozilla posted JavaScript results from tests run not only in SunSpider -- a benchmark developed by the team responsible for WebKit, the browser engine that powers Chrome and Safari -- but also in Mozilla's own Kraken and Google's V8.

In two of the three tests, Firefox 4 Beta 7 proved three times faster than Firefox 3.6.12, the current production build. (Mozilla said V8's results showed Firefox 4 was five times faster than 3.6.12.)

"We knew we needed another major upgrade for Firefox 4 to make us fast all around," said David Mandelin, a Mozilla engineer who worked on JagerMonkey, in a September blog post that Mozilla cited yesterday.

Among other changes to Firefox 4 in Beta 7 were hardware acceleration in both Windows and Mac OS X, support for the WebGL 3D graphics standard, and support for the OpenType font format.

For the first time, Firefox now accelerates aspects of content rendering and page composition when running in Windows XP, Windows Vista and Window 7, as well as in Mac OS X.

Browser hardware acceleration shifts some tasks from a computer's main processor to its graphics processor to boost performance, especially of graphics-intensive chores like rendering video or complex three-dimensional objects.

Like Microsoft, which offers hardware acceleration in IE9, Mozilla relied on the Direct3D API (application programming interface) to boost page compositing in Windows. Mozilla, however, went one step further, accelerating page compositing, though not content rendering, in Windows XP.

Microsoft's IE9 will not run on Windows XP because the still-popular operating system doesn't support Direct2D, the API IE9 uses to boost content rendering.

Firefox 4 Beta 7 on the Mac uses the cross-platform OpenGL API to accelerate page composition.

The Linux version of Firefox 4 does not yet have hardware acceleration switched on, due, said a Mozilla engineer, to driver issues.

The delay was due to problems pinning down bugs in Beta 7 -- which was originally scheduled to debut eight weeks ago -- and waiting for the JagerMonkey team to integrate the new compiler into the JavaScript engine. Late last month Mozilla announced that it was pushing back the release date, once targeted for before the holiday season, into early 2011.

But the browser's development schedule remains aggressive, with three more betas before the end of the year. Mozilla, however, has tacitly acknowledged that the early 2011 final release is tentative, and could slip. "We will not ship software before it is ready," said Mike Beltzner, director of Firefox, when Mozilla announced the delay last month.

Firefox 4 Beta 7 can be downloaded for Windows, Mac OS X and Linux from Mozilla's site.

Firefox 4 Beta 7 is about three times faster than the older 3.6.12, and lags behind only an alpha of Opera 11 in JavaScript speeds. Smaller results are better.

Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer or subscribe to Gregg's RSS feed. His email address is gkeizer@computerworld.com.

Read more about browsers in Computerworld's Browsers Topic Center.

This story, "Firefox 4 regains speed mojo" was originally published by Computerworld .

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