-primarysound
From FTE
-primarysound
This switch will force FTE to use DirectSound's primary buffer output for
sound instead of secondary buffer output.
Note: Normally the game will use the secondary sound buffer because it is more
compatible across more hardware. If you know that your hardware is 100%
DirectX DirectSound compliant you can use this setting in order to increase
the performance of the game. However when you switch the focus away from QW
(task-switch).