On an older gaming system and it seems like fire pits and running smelters give me the most FPS issue. Larger structures do it as well and as the structures get larger that lag gets more and more noticeable, especially with a hammer equipped.

Have two smelters and two charcoal furnaces at a smiting base and running all 4 puts me into a minor slide show as bad or worse than my much larger main base structure.

Not sure if it's lighting, particle effects or some other issue but it would be nice to have performance settings for them.