Sorry, I should have stated that my video clip was 1080p 24 fps. I have the same problem with 1080 60fps. I have an i7-920 processor (I realize it is older and slower), a GTX260 video card, and 18 Gb ram, and 7200 rpm hard drive. It is just wierd that Filmora would play back smoothly and PD15 would not. As a matter of fact, Windows Movie Maker plays back more smoothly that PD15.