Apple (AAPL) touts Safari 4, released as a public beta this morning, as the world’s fastest Web browser for Mac and Windows PCs and after using if for a short time, it’s tough to disagree. Safari 4 is fast - three times as fast as Internet Explorer 7 and Firefox 3, if Apple’s typically hyperbolic claims are to be believed (and I’m not suggesting that they should be). That boost in speed is thanks largely to a new Nitro JavaScript engine (based on WebKit) which run JavaScript up to 4.2 times faster than Safari 3, 30 times faster than IE7 and three times faster than Firefox 3, again according to Apple.

Among the browser’s new features: an Opera-like Top Sites, which displays a mosaic of frequently visited pages; a Cover Flow visualization of browsing history that allows users to peruse previously viewed Web sites as they would albums in iTunes; improved tabbed browsing; and Full Page Zoom, for a closer look at any website without degrading the quality of the site’s layout and text.