Performance Improvements

[JaffaKetchup]

This is designed to reduce the time it takes to generate the list of tiles within a region, as well as any other improvements I can make.

For example, using:

final tiles = List.generate(n, (i) => i, growable: false);

...is considerably faster than using:

final tiles = [];
for (int i = 0; i <= n; i++) tiles.add();