Deferred Settings

Every change to 3-D sound buffer and listener settings causes remixing, at the expense of CPU cycles. To minimize the performance impact of changing 3-D settings, set the DS3D_DEFERRED flag in the dwApply parameter of any of the IDirectSound3DListener8 or IDirectSound3DBuffer8 methods that change 3-D settings. Then call the IDirectSound3DListener8::CommitDeferredSettings method to execute all of the deferred commands at once.

Deferred settings are overwritten by immediate settings. For example, if you set the listener velocity to (1.0, 0.0, 0.0) with the DS3D_DEFERRED flag and then set it to (2.0, 0.0, 0.0) with the DS3D_IMMEDIATE flag, the velocity becomes (2.0, 0.0, 0.0) and does not change when CommitDeferredSettings is called.