The reason why flash sucks on mac? well that lies down to apple not wanting to comunicate and help adobe create a better viewer experience with flash on mac. It works fantastically with windows, because window's help adobe to give window's users a better experience naturally. and that's what apple should be doing at the moment.
You are buying in to Adobes FUD. Hardware acceleration of Flash only came about in Flash 10, the previous 8 versions (and Future Splash) all performed worse than their Windows counterpart. The differences werent as readily apparent in versions 2-4, but once the complexity of Flash work started to explode with version 5 and the introduction of a more powerful scripting language we started to see the difference.
Having said that Apple hasnt made it easy, not necessarily blocking Adobe, but they have had to transition Flash Player from to OS X, then to Intel thats two pretty big lifts for a comparatively small team (Adobe has less than 100 employees per product, Apple has more than 500 non-retail employees per product).
Adobes problem right now is three-fold:
Flash isnt really an ideal format for mobile devices, Adobe is effectively hoping/waiting for the mobile CPU/GPU to reach a point where Flash is viable. Heres the thing when Macromedia owned Director and the web came along the paradigm of multimedia delivery shifted immensely. We went from limited storage and fast bandwidth (650MB on a CD-ROM) to unlimited storage and narrow bandwidth (The Internet and 56K modems). Macromedia tried to shoe-horn Director on the web, but it met with limited acceptance, because Director simply wasnt designed to work within the confines of the Internet. So they bough Future Splash which was ideally suited for Internet delivery, small, vector based instructions sets that could offload the heavy lifting to the CPU. Well mobile has changed all this again, the delivery platforms confines are now battery life and interaction model are the constraints. The sad part about all of this is they should have seen it coming. Ive worked with Flash on mobile devices for nearly 10 years and its always been a compromise.
Secondly they lack focus, they have too many products and too few employees to properly support them. They need to sell/spin-off 80% of their product library and basically support the main products of the CS suite (e.g. no fiddling with the minor apps like Bridge or Contribute - there are better solutions) and the Flash & Acrobat platform.
Flashs fate is outside of their control. It all depends on how the tablet market plays out. If it follows the iPod model where Apple effectively creates a market and goes on to dominate then Flash will go the way of Director. If it goes the way of the phone market and if they can get Flash running reasonably well across all phones but iOS its got a shot.
Ironically Google and Adobe could prove to be the ideal partners moving forward. Google desperately needs a designer-centric developer community for Android and the only one larger & arguably more creative than Apples is the Flash community. Best chance for Google is to deeply integrate Flash into Android at the hardware level and make an official Android/Flash Development environment.