I have a screaming fast rig (check my profile) with a RAID array for source audio (uncompressed PCM 96 Hz / 24bit) that is getting bogged down during preview. 24 tracks of audio, 7 stereo busses. Each instrument track has an instance of Izotope Alloy, and the 4 vocal tracks each have an instance of Izotope Nectar.
Preview plays smoothly if I solo the vocal tracks, but stutters or outright freezes if I solo the instrument track. Preview immediately chokes and Vegas freezes when all tracks are played together.
CPU and disk usage are low. I've also increased track and event buffers to no avail. Where is my bottleneck? It seems that Vegas should handle this, but I can't figure out why not.