Comment 7 for bug 1438383

This is normal behavior, there is one thread doing both the UI and library work (I think? there may be some cases where we do stuff in the background), so when the library is doing something complicated (loading a new track) it might cause the GUI to pause. The audio thread is kept higher priority to prevent dropouts.

We do constantly work on this type of performance issue, but for now I'm going to say this is Invalid because it's a result of the design we've chosen.