Attempts an optimisation for power_change

- Adds an alternate, hopefully faster list iteration method for machines in power_change
- Removes uses of INVOKE_ASYNC for power_change, since it's slower than normal proc calls and does nothing since it doesn't sleep
TODO: Diagnose what the fuck is making power_change so slow anyway.

code/game/area/areas.dm

@@ -310,7 +310,7 @@ GLOBAL_LIST_EMPTY(teleportlocs)
 				A.power_light = FALSE
 				A.power_equip = FALSE
 				A.power_environ = FALSE
-			INVOKE_ASYNC(A, .proc/power_change)
+			A.power_change()
 	STOP_PROCESSING(SSobj, src)
 	return ..()
 
@@ -544,15 +544,19 @@ GLOBAL_LIST_EMPTY(teleportlocs)
 // called when power status changes
 
 /area/proc/power_change()
-	for(var/obj/machinery/M in src)	// for each machine in the area
-		M.power_change()				// reverify power status (to update icons etc.)
-	if(sub_areas)
-		for(var/i in sub_areas)
-			var/area/A = i
-			A.power_light = power_light
-			A.power_equip = power_equip
-			A.power_environ = power_environ
-			INVOKE_ASYNC(A, .proc/power_change)
+	if(contents.len < GLOB.machines.len) // it would be faster to loop over contents
+		for(var/obj/machinery/M in src) // for each machine in the area
+			M.power_change() // reverify power status (to update icons etc.)
+	else // it would be faster to loop over the machines list
+		for(var/obj/machinery/M as anything in GLOB.machines) // for each machine
+			if(get_area(M) != src) // in the area
+				continue
+			M.power_change() // reverify power status (to update icons etc.)
+	for(var/area/A as anything in sub_areas)
+		A.power_light = power_light
+		A.power_equip = power_equip
+		A.power_environ = power_environ
+		A.power_change()
 	update_appearance()
 
 /area/proc/usage(chan)