Alright only way to fix it was to start a completly new world. Not really the outcome we wanted, but I figured we had corrupted chunks and apparently alot of them.
Already did that! Waiting for the respond. Was thinking something like that would be the Issue. I'll leave the post up for now and will post if they could fix it.
Noone having an idea how this could be caused? 😞
@tecu what exactly do you mean by optimizing? RegionFixer didnt work at all, guessing its outdated. Is MCEDIT the only other way?