Revert the map loader optimization

Reverts #24764

code/controllers/subsystem/mapping.dm

@@ -106,14 +106,18 @@ var/datum/controller/subsystem/mapping/SSmapping
 	if(last)
 		QDEL_NULL(loader)
 
+/datum/controller/subsystem/mapping/proc/CreateSpace()
+	++world.maxz
+	CHECK_TICK
+	for(var/T in block(locate(1, 1, world.maxz), locate(world.maxx, world.maxy, world.maxz)))
+		CHECK_TICK
+		new /turf/open/space(T)
+
 #define INIT_ANNOUNCE(X) world << "<span class='boldannounce'>[X]</span>"; log_world(X)
 /datum/controller/subsystem/mapping/proc/loadWorld()
 	//if any of these fail, something has gone horribly, HORRIBLY, wrong
 	var/list/FailedZs = list()
 
-	if(world.maxz != ZLEVEL_SPACEMAX)
-		WARNING("world.maxz does not match ZLEVEL_SPACEMAX!")
-
 	INIT_ANNOUNCE("Loading [config.map_name]...")
 	TryLoadZ(config.GetFullMapPath(), FailedZs, ZLEVEL_STATION)
 	INIT_ANNOUNCE("Loaded station!")
@@ -121,6 +125,9 @@ var/datum/controller/subsystem/mapping/SSmapping
 	if(config.minetype != "lavaland")
 		INIT_ANNOUNCE("WARNING: A map without lavaland set as it's minetype was loaded! This is being ignored! Update the maploader code!")
 
+	for(var/I in (ZLEVEL_MINING + 1) to ZLEVEL_SPACEMAX)
+		CreateSpace()
+
 	if(LAZYLEN(FailedZs))	//but seriously, unless the server's filesystem is messed up this will never happen
 		var/msg = "RED ALERT! The following map files failed to load: [FailedZs[1]]"
 		if(FailedZs.len > 1)