Originally posted by Esos:

- but why this game so laggy when having a huge building or having a lot of stuff nearby even when running in Vulkan. -

Originally posted by Weaver:

- So every single pole, every single fire, every single decoration you place has to be tracked separately. It can't be combined. So instead of tracking dozens or hundreds of active objects, it now has to track thousands or tens of thousands of different objects, these are you "active instances".
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Lots of little buildings nearby won't be better than a large one if they are in the same area, as they are still all active instances at the same time. -

Even if your buildings are loaded at the same time, having them smaller and disconnected should, at least in theory, improve performance. The game is constantly checking if each individual piece of the building is stable. Smaller and disconnected buildings make those calculations easier.