short progress update:
I've reduced the number of tiles shown during rotation using rotated polygon overlap checking. The number of shown tiles is now about 14 vs 56 previously What remains to be seen is how demanding is the overlap checking in comparison to drawing more tiles than needed. Still -> less tiles drawn = less tiles down/loaded = less IO.
I'll do the map overlay optimizations next and I'm also working on quite a few other things in parallel.
Q/A -> soon