OK. Well the patch looks pretty straightforward. (Though, for what it's worth, those Pan Spin Zoom actors are a bit expensive CPU wise.) That being said, a couple of questions:

1) You're using a lot of pictures. Most of them are JPEG, but a couple are PNG. I wonder if the PNGs could be somehow causing trouble. If it's not a big deal, I'd change those PNGs to JPEGs just to see if it helps.

2) What is the resolution of those pictures -- if they are not consistent, then perhaps a range. A common mistake  is to use pictures that are _way_ beyond the resolution of the video projector. (Often, people just are thinking about it; they export from their camera software and import into Isadora; but the resolutions are like 4096 x 3192 or whatever. Those are big images to load, and not necessary since the projectors at most are 1920 x 1200.)

3) The main movie clips are AVI files. I assume you have the "Windows Native Playback" option turned on in the Isadora Preferences?

Let me know if any of these suggestions help or trigger an insight for you.