I recently edited a video in after effects with my iMac 2011 computer with 12 GB of ram, and i went ahead to preview it in quicktime player.

The problem is, my quicktime player was so laggy it was un viewable. Granted that i added a whole ton of effects and some motion tracking, but i don't see how that would hinder the quicktime player. The frame by frame scrolling works flawlessly, meaning that the rendering went smoothly i just can't consistently get a real time playback in QT.

Any help? thanks.