after having installed OSX Mountain Lion my sound startet stuttering whenever there is rapid movement on my screen.
This includes e.g. window movement, scrolling through image loaded websites or video playback (flash player, quicktime).
A restart didn't help. I'm using stereo output, not digital.
I have connected a second monitor but the problem persists after disconnecting it. Movement on the second monitor also causes the sound to stutter.
My GPU Diode temperature is at 85°C (there is some bug that keeps the GPU under load while a second monitor is connected AFAIK), but I guess it was the same under Snow Leopard.
In Snow Leopard the sound output was always perfect even under heavy load or heavy HDD I/O.