In a 2012 thread about a case of OsmAnd being slow at rendering, one person advises this:
verify that you use Native Library (which definitely speed up rendering process)
And the replies seems to imply it works:
I selected the Native Library and deleted Ind.cache file. It has nearly doubled the rendering speed of my map.
I have the same problem of slow rendering, but I can't find the Native Library setting.
QUESTION: How to enable the Native Library in recent OsmAnd?
I am using OsmAnd~ 1.8.3 from F-Droid: