I think I just found it by accident. Haven’t proven it yet though.
If you go to Preferences/VST-Plug-Ins there’s an option that says “Suspend VST3 plug-in processing when no audio signals are received” and it wasn’t ticked. I knew VST3 had this feature but didn’t know it was a Preference setting. I shall post when I’ve verified any time reduction…
Setting on took ~30 seconds.
So that seems to be the issue.
peakae: I found other pasts back in November about CPU peaks, suggesting turning this setting off was a cure. I shall keep an eye/ear out for this…