I have a puzzlement about the performance of iDVD 6 running on three different Macs, and I'm wondering if any of you might be able to provide a logical explanation. The symptoms make no sense to me:

1. Running on a 1.25 GHz G4 iMac (PPC, 1 Gig memory, OS 10.5.8) an 8-minute iDVD 6 project took about 90 minutes to create a disk image.

2. Running the same iDVD project file on a 1.42 GHz G4 iBook (PPC, 512 M memory, OS 10.5.8) took about 35 minutes to create the disk image.

3. Running the same iDVD project file on a 1.33 GHz G4 iBook (PPC, 768 M memory, OS 10.4.11) took 17 minutes to create the disk image.

A month ago I did a much longer video (~80 minutes) and ran into the same symptoms: the 1.42 GHz iBook created the disk image in about 11 hours, while the iMac took about 23 hours (and then the image from the iMac would not play correctly, even though the iMac said "image created successfully.")

The iMac has no trouble at all with iMovie 6 in creating the iMovie projects and then creating iDVD projects with iDVD. It's just the burning of the disk image that goes haywire on the iMac.

I'm wondering if there's some sort of congenital incompatibility between iDVD 6 and OS 10.5. I'm skittish about reinstalling OS 10.4 on the iMac to test this notion since it's such a pain to revert to an earlier OS on a Mac.

Could this be some sort of memory problem on the iMac? It came with 512 M and I upgraded it to 1 Gig after a few years.

Lest you suggest it, I'm not in the market for an Intel-based Mac. For my purposes, the iLife 6 package is the best they've offered and I plan to stick with it.

Thoughts and suggestions would be most appreciated!

Chuck McKinley