Thanks, J-S-Q. 
I’ve decided on just recreating the project in .20 and starting fresh. The project was getting too large and unstable, too many virtual instrument, too long to load, etc. 10GB+ project (in RAM).
I don’t fault Cubase for this, as I’ve had similar experiences in other DAWs with projects even a bit smaller. Which, ironically (predictably?) is the reason I switched back (again) to Cubase a couple years ago. It was much more stable at dealing with larger projects.
Anyway, I’ve decided to “simplify” my setup. I built a new ultra-low-latency DAW just for hosting the virtual instrument and the stacks of insert effects they hog.
In addition to keeping my main DAW light and more stable, it’s also giving me a creative, “playable” workstation, again.