Problem
Audio stutter occurs when playing back videos using Flash player. The CPU is not overloaded and network bandwidth is available.
Solution
In my case this was caused by Flash Player 11. I don’t know what they’ve done in that version but it simply won’t playback videos without audio stutter regardless of what web browser hosts the plugin.
The solution was to uninstall Flash 11 and install version 10.3. Links to the installers can be found here:
Where can I find direct downloads of Flash Player 10.3 for Windows or Macintosh?