Hi Chris,
Premiere acceleration is provided by one of these cards:
GeForce GTX 285
GeForce GTX 470
Quadro CX
Quadro FX 3800
Quadro FX 4800
Quadro FX 5800
Quadro 4000
Quadro 5000
Quadro 5000M
Decklink in some case may actually slow Premiere down, since it then provides output to your display.
Premiere should absolutely be able to play native AVC Intra in real time, even with several effects, we do it almost everyday. Heck, we throw in 10 Bit 1080P uncompressed on a regular basis, not a frame dropped.
Try using the Adobe Player instead of BM in your preferences and see if things improve.
Vince Becquiot
Kaptis Studios
San Francisco – Bay Area