Earlier last month, I found that YouTube’s HTML5 beta wasn’t even worthy of being beta.  Three weeks after that, Jan Ozer ran some CPU performance tests between YouTube Flash and HTML5 on Mac OS X and Safari and found that CPU performance was better on HTML5.  However, my tests (using same 720P video posted by Jan) on Windows with Google Chrome showed that both are equally bad CPU hogs, but HTML5 was also very buggy and still had very bad image quality.

Test bed:

• Windows Vista x86
• Chrome 4.0.223.16 running HTML5
• Chrome 4.0.223.16 running Flash 10.0.45.2
• Intel Yorkfield 3.2 GHz @ 3.6 GHz
• Process Explorer for measuring CPU cycles

Notes on YouTube HTML5:

• Time slider and pause button very buggy and doesn’t work most of the time
• Video would often pause while audio continues to play
• Forward download progress indicator completely broken (shows all red)
• Doesn’t seem to cache well or at all (perhaps the cause of choppy playback)
• Still very poor image scaling quality

CPU cycles used for the entire video playback:

• 454 billion CPU cycles Chrome 4.0.223.16 (HTML5)
  457 billion CPU cycles Chrome 4.0.223.16 (Flash 10.0.45.2)

This was roughly 15% average CPU utilization across all four 3.6 GHz cores.  YouTube with HTML5 was just as much a CPU hog as with Flash.

Note that I really don’t like flash because of all its security vulnerabilities and because it is extremely slow on slower notebooks and netbooks.  Microsoft Silverlight works well with video even on a low-end netbook.

Image quality test:

HTML5 screenshot crop left, Flash screenshot crop right

You can download the full HTML screen cap here, and the full flash screen cap here.

As you can see, the image is jaggy with HTML5 rendering while the flash sample is smooth.  I even noticed that YouTube Flash at 360P looks better than YouTube HTML5 at 720P.