A small follow-up to this …
Recently map rendering in OsmAnd on my Fairphone 3 felt very slow, when on my similarly set up Fairphone 2 it stayed as fast as I was used to, so map rendering on the inferior (hardware-wise) Fairphone 2 was much faster. Can’t be, I thought.
I compared the OsmAnd settings of the two, and this made the difference:
Settings - Configure map - Map magnifier was somehow set to 25% on the Fairphone 3 (I didn’t do it, at least not deliberately) … setting it to 100% returned the map rendering performance to what it should be.