Without getting to techie on this the reason that the MAC player is slower is to do with the operating system.

On the PC, the player plugs into the native Windows commands for screen rendering, therfroe less calculations have to be made.

On the Mac however, the player cant do this, and so new commands had to be written fot the software to control the appearence on screen. This takes up more CPU time

The new shockwave player uses external hardware for rendering to make more use of 3D. To add this functioality to the flash player is likely to greatly increase the foot print of the player.

Who knows though for flash 6 ?

P