fix(zas): small optimaze zas

code/game/turfs/simulated.dm

@@ -56,6 +56,16 @@
 		holy = TRUE
 	levelupdate()
 
+/turf/simulated/Destroy()
+	if (zone && !zone.invalid)
+		// Try to remove it gracefully first.
+		if (can_safely_remove_from_zone())
+			c_copy_air()
+			zone.remove(src)
+		else	// Can't remove it safely, just rebuild the entire thing.
+			zone.rebuild()
+	return ..()
+
 /turf/simulated/proc/AddTracks(typepath,bloodDNA,comingdir,goingdir,bloodcolor=COLOR_BLOOD_HUMAN)
 	var/obj/effect/decal/cleanable/blood/tracks/tracks = locate(typepath) in src
 	if(!tracks)

code/game/turfs/turf_changing.dm

@@ -22,7 +22,7 @@
 	ASSERT(N)
 
 	// This makes sure that turfs are not changed to space when one side is part of a zone
-	if(N == /turf/space)
+	if(ispath(N, /turf/space))
 		var/turf/below = GetBelow(src)
 		if(istype(below) && !istype(below,/turf/space))
 			N = below.density ? /turf/simulated/floor/plating/airless : /turf/simulated/open

code/modules/ZAS/Zone.dm

@@ -65,9 +65,6 @@ Class Procs:
 
 	var/datum/gas_mixture/air = new
 
-	var/list/graphic_add = list()
-	var/list/graphic_remove = list()
-
 	var/datum/lazy_value/zone_movables/movables = new
 
 /zone/New()
@@ -170,11 +167,12 @@ Class Procs:
 		if(istype(T))
 			T.create_fire(vsc.fire_firelevel_multiplier)
 
+	var/list/graphic_add = list()
+	var/list/graphic_remove = list()
+
 	if(air.check_tile_graphic(graphic_add, graphic_remove))
 		for(var/turf/simulated/T in contents)
 			T.update_graphic(graphic_add, graphic_remove)
-		graphic_add.len = 0
-		graphic_remove.len = 0
 
 	for(var/connection_edge/E in edges)
 		if(E.sleeping)