Your comments

You're going for the more gold then god achievement?^^

Btw, Cian I can confirm it. As bigger the vault is, as bigger the performence drop will be, especially when you conect 2 big vaults.

I've seen that bug often.
We have an ticket for that as well
https://brightrockgames.userecho.com/topics/1997-mp-black-tiles-or-down-tiles-are-visible-when-your-workers-fight-for-ground


It really often happens, when workers try to claium the ground which is in the area of an outpst

Screenshot how it should look like (Skrimish)



I can confrim that looks on Empire Prison.
I can not confirm it for Pre-placed Sanctuary via the Map Editor

If you were asking me,
I don't know, restarted my PC and it was fixed.

Can confirm that