You're suggesting something too major as if it were easy to do. Dividing the screen into sections wouldn't do anything by itself. If you multithread those sections, it might. But I'm not sure whether you are suggesting multithreading or not.

Minecraft uses chunks because it has an infinite map, not because of performance reasons.


If we add multithreading, it's not going to break saves. And if some saves do break, that's just the cost of making such a huge improvement to the game. Multithreading isn't planned to happen soon because of how complex it would be to implement. But I would like it eventually.