I'm playing on my MacBook, and it takes some doing to get the game to start in the first place (I wound up putting it into Vista compatibility mode, with a desktop. The startup screen isn't rendered properly, but there is a link to play the game) When the game starts to use a lot of memory, though, the sound degrades -- the first half second doesn't play, then if there's a significant load, the audio skips and repeats. The casino in episode 3 is particularly bad.
Still, I've been able to play through the first four with only those minor problems.