The playback becomes choppy after a few seconds of playback. I'm using MP4 from a GoPro. Playback is at 1/2 resolution and have cleaned out media cache database. There aren't real effect and very minor editing so it shouldn't be any memory issue.
I'm on a iMac 2.7ghz i5 with 8GB RAM in OS 10.8
6GB RAM dedicated for PP
Anyone able to help?