Currently Being ModeratedMay 3, 2013 12:05 PM (in response to Pallisgaard)
First delete any files that start with 'com.apple.itunes.*' in ~/Library/Preferences/ByHost/. This will clear your iTunes preferences.
Next, open Terminal.app and run each line one at a time:
defaults write com.apple.iTunes file-buffer-size 512000
defaults write com.apple.iTunes stream-buffer-size 512000
You may need to experiment with the number, but 512000 works well for me.
Disclaimer: iTunes may or may not decide to use these preferences, so it's entirely possible that it fails to read these values and they don't have any effect. With that said, I do seem to notice far fewer skips and stutters with the 'buffering stream' window popping up after having set this.