According to Apple boss Steve Jobs, the company's Safari browser is the fastest on the market. However, Apple has something of a history with benchmarks: when the PowerMac G5 was introduced in 2003, for example, the company was accused of tweaking its test system and hobbling rival Intel-based machines. Since then, of course, Apple has come round to the attractions of Intel processors.

Jobs' statement that the fastest Safari browser is based on tests the company has carried out using iBench 5.0. However, these benchmark results should be treated with caution: manual measurements with a stopwatch show that Safari is not quite as fast as iBench suggests. This is because, as mentioned earlier, iBench uses the JavaScript 'onload' event to determine page loading time, which Safari triggers before the page has in fact finished loading. Even so, despite these caveats, there's no doubt that Safari is indeed a fast browser.

Safari 3.1.0 is quickest in the HTML tests with a time of under 10 seconds, placing it well ahead of Opera 9.27's 48 seconds. However, the STAND Safari plug-in extends the load time to over 18 seconds — perhaps because it prevents the premature page-loading statement normally reported by iBench. The beta version of Opera 9.5 manages to reduce the load time from over 48 seconds in version 9.27 to less than 20 seconds. In the XML/CSS test, Safari again takes first place — and here, the STAND plug-in has no significant impact on performance. Opera brings up the rear in this test, and this time the 9.5 beta brings no improvement.

Safari is the winner in the JavaScript tests too. These tests also demonstrate the benefits that browser development can deliver. Among the beta versions, Firefox 3 Beta 5 is particularly impressive compared to its predecessor, reducing Firefox 2.0.13's 3.91 seconds to just 1.07 seconds in the HTML/JavaScript DOM test. Opera and Safari also deliver significant performance improvements in their respective betas.

Timings in seconds: shorter bars are better.

Timings in seconds: shorter bars are better.

Of the current Mac OS X browsers, Safari 3.1 is clearly the fastest in the SunSpider JavaScript benchmark. However, Firefox 3 Beta 5 beats Apple's browser by a noticeable margin. Elsewhere, the Opera 9.5 beta improves on its predecessor, although it cannot match the performance of Safari and Firefox 3 Beta 5.

The individual tests show exactly how Firefox 3 Beta 5 has overhauled Safari, and where Opera needs to improve in order to catch Firefox and Safari. For example, Firefox 3 Beta 5 took 187 milliseconds for the bit operations test, compared to the current version's 2,241ms. Opera 9.5 Beta also improves on the current version, but not to the same extent.