The test, from Streaming Learning Center, was conducted in response to recent comments alleged to have been said by Apple co-founder Steve Jobs, in which he reportedly called Flash a "CPU hog." While the test found that HTML5 is significantly more efficient than Flash on the Mac when running the Safari Web browser, those same advantages do not exist on other Mac browsers, or in Windows.
"It's inaccurate to conclude that Flash is inherently inefficient," author Jan Ozer wrote. "Rather, Flash is efficient on platforms where it can access hardware acceleration and less efficient where it can't. With Flash Player 10.1, Flash has the opportunity for a true leap in video playback performance on all platforms that enable hardware acceleration."
The report noted that Apple has not enabled the hooks to allow GPU-based acceleration for H.264 video decoding. Anand Lai Shimpi, founder of AnandTech, asserted "it's up to Apple to expose the appropriate hooks to allow Adobe to (eventually) enable that functionality."
Adobe's update to Flash 10.1 on the Mac improved CPU efficiency within Safari by 5 percent, but the Web format still trails far behind HTML5 due to hardware acceleration. With Google Chrome, neither were particularly efficient, and Firefox saw slightly better performance than Chrome.
On Windows, Apple's Safari browser doesn't play HTML 5 content. But the Google Chrome browser in Windows played Flash 10.1 content with 58 percent more efficiency than HTML5.
HTML5 is not natively supported in Firefox or Internet Explorer, but the update from Flash 10 to Flash 10.1 improved CPU performance for the browsers by 73 percent and 35 percent, respectively. Flash 10.1 in Windows offers added hardware acceleration.
"When it comes to efficient video playback, the ability to access hardware acceleration is the single most important factor in the overall CPU load," Streaming Learning Center noted. "On Windows, where Flash can access hardware acceleration, the CPU requirements drop to negligible levels.
"It seems reasonable to assume that if the Flash Player could access GPU-based hardware acceleration on the Mac (or iPod/iPhone/iPad), the difference between the CPU required for HTML5 playback and Flash playback would be very much narrowed, if not eliminated."
Google added support for the most popular video destination on the Internet, YouTube, in January. The beta opt-in program is available only for browsers that support both HTML5 and H.264 video encoding.
Scrutiny over Flash has grown in recent months since Apple introduced its multimedia iPad device, which does not support the Web format from Adobe. Apple, instead, has placed its support behind HTML5.
For more on why Apple isn't likely to add support for Flash in the iPhone OS, read AppleInsider's three-part Flash Wars series.