Choppy zooms and pans

I’m using FM 2.6.2. When I export my FM slideshow to an HD video and play it back in QuickTime Player, zooms or pans aren’t smooth but are a bit “jerky.” Cross-fades look fine. I’ve tried frame rates of 30, 50 and 60 fps, and have the same problem every time. I’m working on this slideshow for an event this Friday, and the rest of the slides for the event will be run from a Windows computer, so I need to get it in a format that works on Windows. Any suggestions?