BetaNews: 
Mozilla Wednesday released a significant update to the beta of its Firefox 4 browser. The update adds a new JavaScript JIT compiler, going by the name of JägerMonkey, and improves the browser’s support for hardware acceleration, OpenType fonts, and WebGL 3D graphics (the technology used to create an HTML5 version of Quake II back in April.)
Additionally, the latest beta includes a stable add-ons API, so developers can finally update their add-ons to Firefox 4.
Of course, the first thing Mozilla is touting about this version of the browser is the performance boost it gets from the new JägerMonkey JavaScript compiler.
“The Firefox SpiderMonkey JavaScript engine now incorporates the new JägerMonkey JIT compiler, which, along with enhancements to the existing TraceMonkey JIT and SpiderMonkey’s interpreter, add up to speeds that really show off today’s rich Web apps. You’ll notice this in faster start-up time, improved page-load speed and the performance of Web apps and games,” Jay Sullivan wrote in the Mozilla Blog today.
In Scott Fulton’s Browser Performance tests in October, he ranked Firefox 4 Beta 8 behind both Opera and Chrome, but well ahead of Safari and Internet Explorer. At the time, however, the feature-complete version of Beta 7 was not available for testing.
That milestone has been reached, and it can be downloaded now.
Using the Kraken and Sunspider benchmark test suites, Mozilla says FF4 beta 7 runs 3 times faster than beta 6; and in the V8 Benchmark suite, it counts a 5x improvement.