I’ll give it a try within a day or two. I didn’t previously because by the time you kindly posted it I had already backed-up almost everything manually. But I realize now that I probably didn’t communicate that though! Thank you @Mark_S
And, of course, a huge thank you to @simon ! Speed seems to be as normal now! Regarding:
installing a robots.txt file to instruct web-crawlers not to relentlessly follow every filter and sort link in the “Explore” page.
…it’s a bit strange though that the problems arose suddenly, not gradually, so if web-crawlers were always “following every filter…” then why would it change all of a sudden…? Or maybe they themselves, or how they do their thing, changed ~2 weeks ago? Or maybe there was a sudden influx of users? Or an abrupt change in how users use the system?