An Intel Core2 Duo Mac Mini, with no graphics card to speak of (so this couldn't skew the results even theoretically) plays 720p H.264 YouTube-encoded videos with ~9% CPU usage, and no hiccups, the frame-rate is evenly distributed, every frame lasts for whatever time it should. Compare and contrast with the Flash decoder, that ceilings at about 70%, and plays un-evenly, even on a frame-by-frame level -- there is no way of telling how much time a given frame is showing on the screen.

That's why many will use Rentzsch' Click-to-Flash WebKit plug-in, to block all Flash permanently and play H.264 movies natively. github.com/rentzsch/clicktoflash

Here's another one, this time from Firefox for Maemo RC3:

> We’ve decided to disable plugin (not to be confused with add-ons, which are supported) support for this release. The Adobe Flash plugin used on many sites degraded the performance of the browser to the point where it didn’t meet our standards.