When Apple released Safari 3 last year it claimed that it was the fastest browser available. According to Apple Safari 3 was 4.5 times faster than Firefox 2 in JavaScript performance. That changed when Firefox 3 beta was announced as it almost eliminated the performance gap. According to the latest test done by Ars Technica using SunSpider, Safari 3 and Firefox 3 are very close in performance. But WebKit’s latest build that includes new SquirrelFish JavaScript engine was 1.5x faster than both Safari and Firefox. The same SquirrelFish JavaScript engine will be used in Safari 4 giving it a clear edge on Firefox 3. The SquirrelFish engine is faster for JavaScript because it uses the new just-in-time bytecode interpreter instead of the more common tree-traversal interpreters. According to Ars “Though JavaScript performance isn't the only factor in overall browser performance, the popularity of web application frameworks like SproutCore make JavaScript performance an important consideration. And as web-based applications become more common, Safari could come to be known as the best "platform" for running them.” I totally agree with them, I have been big fan of Firefox (Firefox was my only browser of choice) but since Apple has launched Safari 3, I am using both the browsers equally.