If playback of QuickTime movies and Audio CDs are choppy, slow, skip, or jump around, check the following:
Step 1
If you have a PowerBook, turn off Processor Cycling (in the PowerBook Control Panel).
Step 2
On all Macintosh and PowerBook computers, turn off Virtual Memory (in the Memory Control Panel).
Step 3
Turn off or quit applications running in the background before you try to play the music or the movie.
This article was published in the "Information Alley": Volume II, Issue 4, Page 5