Quicktime player app causes screen updates to lag?

Question

I notice gui refreshes are paused by 0.5 seconds every 20 seconds if quicktime player app is loaded.
Example: Load quicktime player app. Now drag a finder around continuously. On my system, every 20 seconds, the finder window will not follow the mouses movements for about 0.5 seconds. About 0.5 seconds after the pause, the window will start to follow the mouses movements again.
No movie needs to play. There is no load on the machine at all.
There are no errors reported in the system logs.
If I quit the app, the problem vanishes.
If i play movies using VLC, there is no lag at all.
OS X 10.6.1 Server
Mac Pro
NVIDIA GeForce GT 120
Quad 2.94 Ghz
8 gigs rams.
1.2 terrabytes free disk space.
Message was edited by: Adam Chrystie

Answer 1

Ok so after a few rounds of lugging the computer to the Apple Store's genius bar. I narrowed the problem down to my Samsung synchMaster 244T monitor. This monitor works great with my MacBook Pro and linux machines but for some reason it causes my screen lags on the Mac Pro.
I bought an Apple Cinema display and the problem vanished!
Very odd.