code/game/machinery/doors/airlock.dm

/proc/get_airlock_overlay	Overlay cache. Why isn't this just in /obj/machinery/door/airlock? Because its used just a tiny bit in door_assembly.dm Refactored so you don't have to make a null copy of airlock to get to the damn thing Someone, for the love of god, profile this. Is there a reason to cache mutable_appearance if so, why are we JUST doing the airlocks when we can put this in mutable_appearance.dm for everything