i faced the same problem with the new version - the problem which seems to be nonexistent with the old (pre-au) version.
i was able to use multiple instances of vintagewarmer but now with this new version i cannot even use one. in a session where there's one track and vintagewarmer being the only plugin in the session. it plays few seconds, clicks as hell, then stops playback. error 60xx something.
it says there's not enough cpu, but the problem is not with the hardware which was able to drive multiple vintagewarmers in sometimes very plugin-heavy sessions.
there's clearly something wrong about the new version - i sent email to psp support already but have received no answer. not that i wait for an answer... a solution would be better
the same problem seems to have been included with the new mixpack plugs, too. completely unusable.