These games seem to constantly have unused vertices, and this is worst shown in the Shadow Pokemon purification cutscene. The Shadow Pokemon purification cutscene is even worse on XD with forced single core mode, as instead of having FPS dropping with VPS staying 60ish, it will drop both, resulting in audio stuttering. Turning on CPUCall seems to have a 7/8 reduction of draw calls for that cutscene (~800 -> ~100), doubling performance. Many other areas of the game seem to benefit from this setting too, having some kind of performance boost.
The movie config layer is not active for recording, only playback. Thus, recording ends up stuck with default SYSCONF settings.
The fix is simply to add in the movie config layer when recording. The way it's done is a bit hacky, but seems to work.
This should reduce (but not completely eliminate) gradual audio desyncs in dumps. This also allows for accurate sample rates for the GameCube.
Completely eliminating gradual audio desyncs will require resampling to an integer sample rate, as nothing seems to support a non-integer sample rate.
CasualPokePlayer