With Google's Chrome making big market share gains month after month and Microsoft working hard on Internet Explorer 9, the pressure is on stagnating Mozilla to step up its game and stay competitive. In an attempt to spark some interest for the next major upgrade of its open source browser, Firefox team leader Mike Beltzner s for Firefox 4, Mozilla is hoping to release beta versions this summer, possibly as early as June, with the final release shipping sometime around November if all goes according to plans. One significant change coming under the hood is JaegerMonkey, which combines Firefox's current JavaScript engine with elements of those used in Chrome and Safari browsers. Also on the Firefox 4 plan is support for 64-bit processors, a streamlined main thread, and DOM improvements, as well as an overhauled and simplified user interface across all platforms.