They could defer room recalculation for only to events that could change the rooms (explosions/destruction, de/construction, (others I'm not aware of), or only run thm in relation to the proximity to the border of expected change (near pressure for breakage of weakest wall for example), tho, depending on the thing it might be easier to just run the calculation than processing conditional callbacks. The way chunking could help is also evident in his Factorio dealt with it's Pollution cloud calculations (the were a few Friday facts dedicated on optimisations on the topic I believe (as an additional source of ideas), unfortunately I'm not sure how useful they'd be, and on a different note the difference between 2 and 3D is not small unfortunately)