The conclusion:
Overall, it's inaccurate to conclude that Flash is inherently inefficient. Rather, Flash is efficient on platforms where it can access hardware acceleration and less efficient where it can't.Adobe has responded to the CPU Performance gripes and Steve Jobs finger pointing and done a lot to improve performance in Flash Player 10.1.
With Flash Player 10.1, Flash has the opportunity for a true leap in video playback performance on all platforms that enable hardware acceleration.But Apple does not expose the necessary hooks to do hardware accelerated video playback on Macs.
I don't follow the politics of the situation, but after noting significant playback efficiencies in Flash Player 10.1 on the Mac, respected technologist and AnandTech founder Anand Lai Shimpi commented "with actual GPU-accelerated H.264 decoding I’m guessing those CPU utilization numbers could drop to a remotely reasonable value. But it’s up to Apple to expose the appropriate hooks to allow Adobe to (eventually) enable that functionality." So it looks like the ball is in Apple's court.
