Steve, that’s great progress. Those two with thousands of child posts are definitely the likely offenders. Good find!
However, no screenshots came through. 🙁
And I also saw you opened another thread for the same topic at https://theeventscalendar.com/support/forums/topic/very-urgent-issue-with-recurrence-instances/ and got a response there so I will close this one out and let that newer one continue.
Thank you again for your efforts here and sorry this happened.