Sorry to disagree Pierre, but just because your system is experiencing issues, I wouldnt assume that its a problem for everyone. I will say it again. I can play h.264 clips from my 5D just fine.
As to effects,if you have the Nvidia 4000 and use the accelerated effects things are faster. I cut a 4:30 minute dramatic piece on P2 that needed color correction on every clip. Using the PrP 3 way, I was able to see it play in real time AND export was only 3 minutes. When I used Colorista2 I had to render everything and export took 10 minutes. You have to know how the software works and take advantage of its strengths.
Of course transcoding is always an option if your system has issues.
Tom Daigon
Avid DS / PrP / After Effects Editor
http://www.hdshotsandcuts.com
Mac Pro 3,1
8 core
10.6.8
Nvidia Quadro 4000
24 gigs ram
Maxx Digital / Areca 8tb. raid
Kona 3