Tim Hunt

If the question bank is this slow, it is a performance bug and it should get fixed.

There is some work-in progress, the recent things in Epic MDL-86578 - for example this one MDL-85637.

In terms of investigating performance bugs: ... I wrote about this recently. See https://moodle.org/mod/forum/discuss.php?d=469969#p1891630

Best wishes for your retirement - and I hope that in time you will choose to come back as a community member becuase it is nice to see you around - but don't rush it.

Can I also say a huge thank-you for all the help you gave me with many different things during your nearly 15 years working for Moodle. That is on top of the general helpfulness you display to everyone here.

remove_unused_questions is a scheduled task. Sorry not to be clear.

You need transfer_question_categories and transfer_questions to complete. They are an essential parts of the upgrade - but they are done in ad-hoc tasks, so your site does not have to be completely offline for however long the upgrade takes.

delete_unused_questions ... acutally, are you talking about remove_unused_questions ... comes from https://moodle.atlassian.net/browse/MDL-87356. That is about dealing with the "massive problems with question duplication". Letting that task run first - which will delete a lot of unneeded garbage from database, should make it easier to get the transfer_question_... tasks to work.

I don't think there are any easy answers to working this out. It will take some digging.