You can set priorities for the foreground synchronization threads and for the merge thread. Adjusting thread priorities can have a significant impact on system performance.
The <Priority> element controls the priority of the foreground synchronization threads. Setting the element's value to 0 makes the foreground threads run at their default priority level, which matches that of the mm-sync service when it's started. Nonzero values assign absolute priorities.
Running the foreground threads at a priority level two lower than the default priority level may significantly reduce delays when changing tracks. For example, if mm-sync is running at priority 10, you should set the prioity of the foreground synchronization threads to 8: <Priority>8</Priority>.
The <MergePriorityAdjust> element controls the priority of the merge thread, which is a background synchronization thread that writes entries to the files table. By default, this thread runs at a priority one higher than that of the foreground synchronization threads. For example, if the foreground synchronization threads run at priority 10, the merge thread runs at priority 11.