Safari is faster than rival browsers from Microsoft and Mozilla, a North Carolina Web testing firm said Wednesday -- putting proof to Apple's June boast that its browser was the quickest.

Michael Czeiszperger, general manager of Web Performance of Durham, N.C., used his free time -- and some of WPI's tools -- to measure how fast the Windows versions of Apple's Safari, Microsoft's Internet Explorer 7 (IE7) and Mozilla's Firefox 2 grabbed pages.

"I noticed that Apple used canned benchmarks, not actual load time measurements," said Czeiszperger, explaining why he timed the browsers.

Each browser was pointed at the 16 most-trafficked sites as listed by Alexa at the end of August, and the times it took each to render each site recorded. Results over a two-day period, with multiple tests run at different times, were averaged for a final number. The browsers were also timed as they pulled up those sites' saved HTML, which had been placed on a local server. That, explained Czeiszperger, was an attempt to get measurements independent of the vaguarities of Web server loads and Internet traffic conditions.

"In all cases, the Safari 3 Windows beta was the fastest browser in terms of page load time," said Czeiszperger.

But the differences between Safari and IE, and Safari and Firefox, were minimal when the site was pulled from the local cache, not the actual server. "The .2 second difference between Safari beta and Firefox 2, and Safari beta and IE 7 is negligible," Czeiszperger added. "For sites that are accessed frequently, and thus likely to be in a browser's cache, we found no appreciable difference."

When the browsers were pulling a page for the first time, however, Safari was on average 1.1 seconds faster than IE 7, and 1.4 seconds faster than Firefox. "Over a typical 'high speed' connection, this performance increase is likely to be noticeable," said Czeiszperger.

Apple's contention that the beta of Safari 3 for Windows loads pages up to twice as fast as its rivals, however, is a bit of a stretch, Czeiszperger said. In June, when Apple CEO Steve Jobs unveiled Safari for Windows at the Worldwide Developers Conference, he claimed Safari loaded pages twice as fast as IE 7, 1.6 times faster than Firefox. "What we've got here is...the fastest browser on Windows," said Jobs at the time.

WPI's measurements backed up Jobs' claim that Safari was 1.6 times faster than Firefox -- its numbers showed it to be 1.7 times faster -- but not the boast about Safari's thumping of IE. There, WPI's ratio for Safari was only 1.4 times faster -- not twice as fast, as Jobs claimed. The ratios for the page loads from the remote servers and the canned editions on the network were identical, said Czeiszperger in an interview Wednesday. "That was a good validation that the live measurements were accurate," he said.

Czeiszperger's load time measurements are available the WPI site.

Safari 3 for Windows is expected to move from beta to final on Friday, when Apple releases Safari 3 for Mac OS X as part of the new operating system, dubbed Leopard. Safari 3 can be downloaded free of charge from the Apple site.