Minor startup performance improvements (#2177)

changes:

Reduced Asteroid setup time by ~4 seconds on average.
Fixed a bug where jump-to-turf may have not worked on mine turfs.
Possible minor startup time improvements for SSair and Xenoarch.

code/controllers/subsystems/air.dm

@@ -131,7 +131,7 @@ Class Procs:
 	admin_notice(span("danger", "Processing Geometry..."), R_DEBUG)
 
 	var/simulated_turf_count = 0
-	for(var/turf/simulated/S in world)
+	for(var/turf/simulated/S in turfs)
 		simulated_turf_count++
 		S.update_air_properties()
 

code/controllers/subsystems/initialization/asteroid.dm

@@ -19,11 +19,7 @@
 		new /datum/random_map/noise/ore(null, 0, 0, 5, 64, 64)
 		new /datum/random_map/noise/ore(null, 0, 0, 4, 64, 64)
 		new /datum/random_map/noise/ore(null, 0, 0, 3, 64, 64)
-		var/counting_number
-		for(var/turf/simulated/open/chasm in world)
-			counting_number += 1
-			chasm.update()
-		var/counting_result = "Total number of chasms: [counting_number]"
+		var/counting_result = "Total number of chasms: [SSopenturf.openspace_turfs.len]"
 		admin_notice(span("danger", counting_result))
 		game_log("ASGEN", counting_result)
 

code/controllers/subsystems/initialization/xenoarch.dm

@@ -19,7 +19,7 @@ var/datum/controller/subsystem/xenoarch/SSxenoarch
 
 /datum/controller/subsystem/xenoarch/Initialize(timeofday)
 	//create digsites
-	for(var/turf/simulated/mineral/M in block(locate(1,1,1), locate(world.maxx, world.maxy, world.maxz)))
+	for(var/turf/simulated/mineral/M in turfs)
 		if(isnull(M.geologic_data))
 			M.geologic_data = new/datum/geosample(M)