Optimizes asteroid generation

code/game/turfs/initialization/init.dm

@@ -6,7 +6,11 @@
 
 /area/initialize()
 	..()
+	var/list/minerals = list()
 	for(var/turf/simulated/T in src)
-		T.initialize()
+		if(T.initialize())
+			minerals += T
 		if(turf_initializer)
 			turf_initializer.initialize(T)
+	for(var/turf/simulated/mineral/M in minerals)
+		M.MineralSpread()

code/modules/mining/mine_turfs.dm

@@ -85,10 +85,8 @@ var/list/mining_overlay_cache = list()
 /turf/simulated/mineral/initialize()
 	if(prob(20))
 		overlay_detail = "asteroid[rand(0,9)]"
-	if(density)
-		spawn(0)
-			MineralSpread()
 	update_icon(1)
+	return density && mineral
 
 /turf/simulated/mineral/update_icon(var/update_neighbors)