luceos Ok, parameter set to 0 on the hosting. It looks like MariaDB is still not using indexes.
I updated flarum/tags
to 1.1 and it didn't at least kill performance. We'll see if it gets worse if more users enter during the day.
The forum loads over 10 seconds no matter now if it's on 1.0 or 1.1. Strange.
I'm importing the database locally into MySQL. I will let you know in a few hours if there is a performance difference between MariaDB.