Draft: #1010 Confluence check: improve performance by creating zero/old relations only for relevant variables (archive partial solution)
- This is a partial solution only. See #1010 (comment 2839113) for the details.
- I'm archiving this, in case we ever want to attempt this again in the future.
- Given the extra complexity of really making this work, and the good performance achieved by #1006 (closed) in the mean time, I don't think we need to pursue this further at the moment. This is therefore just archived for the future.
Addresses #1010 (closed)