Divisi/voices with VEPRO inefficient playback

Using VEPRO for routing divisi strings is very slow when assigning a instrument.

When dividing multiple strings (violins I and II a2, violas a2 and cello’s a2) playback of fast trills (unmeasured tremolo) is causing crackling with low audio buffer sizes (256).
This problem is not happening without divisi/voices, even for a full ochestra playing fast trills.
So 25 instruments playing without problem, while 6-8 instruments on divisi tracks having problems, sounds like there’s something inefficient about divisi/voices tracks.