Tried continuing on from a 2008 post, but I don't think anyone would be scrolling to the bottom. So started new thread. My iMac i7 860 2.8GHZ 8GB 1033MHz RAM 512MB GPU HD (if important not sure) - 650GB+ free. Vendor: Intel Product: 5 Series Chipset Link Speed: 3 Gigabit Negotiated Link Speed: 3 Gigabit Description: AHCI Version 1.30 Supported ST31000528ASQ: Capacity: 1 TB (1,000,204,886,016 bytes) MAC OSX 10.6.7 It can't handle a full HD playback that I've now rendered from Adobe After Effects. This is a .mov file playing on quicktime. I tried VLC player (latest version) and it still skips frames and freezes for seconds at a time. Activity monitor shows: CPU at 92.7% idle (though, I do see it spike down to 49.9% idle just by sitting here and doing nothing). RAM: 1.36GB free and 4.75GB inactive Processes: 99 I can't see why I should be lagging playing a simple 30second clip. Could anyone help me? Or share some light on this matter?