A benchmark test designed to compare graphics rendering systems in different operating systems has found that Mac OS X performs, on average, at about half the speed of Windows XP.
Sean Christmann, a developer at user interface design firm EffectiveUI, said his GUIMark test was developed to give designers and developers an indication of which technologies can draw complex interfaces at a smooth rate of motion.
EffectiveUI worked with eBay on the company's eBay Desktop application, on which Christmann was a lead developer.
The test was inspired by the Bubblemark animation test, according to Christmann, but was designed to heavily saturate the rendering pipeline and determine the level of visual complexity achievable in a given two-dimensional rendering technology.
Christmann ran the tests on a Macbook Pro with an Intel Core 2 Duo processor running at 2.33 GHz, and with Windows running in a Boot Camp partition.
"I’ve been surprised with the results so far between WinXP and OS X," Christmann said in a blog post. "On the same machine its very clear which vendors take more advantage of the underlying hardware."
For the HTML test, Christmann used the fastest browser on each platform, Safari 3 on Mac OS X and Internet Explorer 7 on Windows. To make the tests as equivalent as possible, anti-aliasing was enabled in Windows at the OS level, Christmann said.
The Windows browser rendered HTML at an average frame rate of 28.36 frames per second (fps), compared to 18.20 fps for Safari 3, Christmann said.
In other tests the disparity was similar or more extreme. Flash, running in Flex 3 in both operating systems, ran at 46.08 fps on Windows and 8.01 fps on the Mac.
Christmann said the poor performance for plug-ins was to be expected. "The results for the different plugin technologies aren’t too surprising since it’s regularly admitted that most companies spend their optimisation time on Windows due to its larger install base," he wrote.
In the case of Flash, however, the results were poorer than expected on the Mac, he said.
"I’m also extremely surprised at the rendering speed that Flash is able to pull off on Windows," he wrote. "I’m considering making the testcase more intensive since Flash is running so fast, but for now maybe the really poor Mac performance will give Adobe something to work on."
While plug-in performance might be related to market share, this factor doesn't account for the sluggish browser rendering times in Mac OS X.
The market share argument "doesn't hold any water though when comparing HTML rendering on Safari/Mac against IE /Windows, where there’s roughly a 1.6 : 1 advantage to the IE team", Christmann wrote. "I can’t help but wonder if the core APIs on the Mac platform are creating any unnecessary roadblocks."
Mac OS X is relatively new to the Intel x86 hardware platform, having run on IBM's PowerPC architecture until 2006. Windows, by contrast, has run on Intel-compatible hardware since its inception.