[BUG] Mini-map square diagonals are mishapen when enlarged

[mrpenguinb]

At the highest resolution and size for the mini-map on a 2560x1440p display, notice the edges of the main grass island in any normal grass/ocean level. The graphics are a bit off on the diagonal corners. More of a nitpick than anything.

Additionally levels take a noticeable amount longer to load when the mini-map is set to a high resolution.