First off, the constitution only protects US citizens.
I see your Bullshit and raise you a Fourteenth Amendment!
atom d550: 8.5W
In the case of the Pentium 4 - no hardware acceleration being available (move to a Radeon HD 4670, they are available on AGP bus and *DO* feature H.264 acceleration, older AGP GPU may lack it)
Pure sloppy programming - if the rest of the Flash implementation is completely b0rked, no hardware accelerated magic can save the situation.
I have an older system that has a 2.4ghz dual-core Opteron and an AGP 4670 (obviously good enough to max out Source Engine games at 1920x1080).
1080p Youtube videos don't play as well as they should. I'm going to lean towards the latter reason for sub-par Flash performance. YMMV.