And if you look for example at page 16 of this topic some features like mini map MAYBE make actual gameplay worst, because it "eats" sprites and / or cpu power that can be used for enemies.
I don't believe
the two are related. Grimlock has been refining enemy placement all along to improve playability (both in the general sense as well as in terms of flicker and slowdown). Changes to enemy placement would be made based on what makes the game most enjoyable.
It's true that the minimap uses up some sprites and takes some CPU time to render, but it doesn't seem to have any significant impact on slowdown, and the map actually renders with lowest priority so it will sacrifice itself instead of causing other sprites to flicker or disappear.