Just clarification, if the red bar inside VI PRO at the voice meter appears, the hardrive streaming capacity is overextended.
So this is not related to VE PRO per se.
Keep in mind that even with SSD drives the possible voice amount is not that high when multiple audiostreams are forced exatcly at the same time. (burst voices)
This might happen pretty often if you use dimension strings triggering all players simultanioulsy, further performing quantised chords with vel Xfade active, also fast movements of all players in unisono could be very demanding for hardrives.
Best option is to set the preload buffersize of VI PRO to a higher value (don't mess this up with the buffer size of the audio hardare),
and also distributing the sample content to different hardrives migt help.
best
Herb