Flash overhead does not appear to be the problem. OSX overhead would appear to be the problem.
When I try to view a Flash file under OSX on my 933Mhz Powermac its dead slow. The same file when viewed with Mplayer under MorphOS works fine.
The only problem using MorphOS to view Flash files is the the primary browser (OWB) has very poor Flash support and the author (Fab) has stated he doesn't intend to improve it (prefering to focus on html5).
Stop bashing OS X, please read:
http://www.roughlydrafted.com/2010/04/14/chronicles-of-conflict-the-history-of-adobe-vs-apple/It's not Jobs fault that Adobe laughed at his PPC/OSX, when Apple struggled to get back to mainstream with this new platform.
And, maybe play the same file with Mplayer under OS X. Ever tried?
As much as I am Amiga/68k fanboy, can't stand bashing mac os x without reason :-).
Regards, ppascal