Misc. Optimizations (#3993)

changes:

Overlays now creates less temporary lists.
Falling no longer queues unsimulated atoms that wouldn't fall anyways (incl. LOs).
Pixel-shifted AO is now cached too.
Changed some references to get_map_cell() to macro equivalents in random maps.
Added smoothing hinting to the icon smoother, allowing for major performance improvements in common cases.
Space initialization no longer involves appearance churn (and is much faster as a result).

code/controllers/subsystems/icon_cache.dm

@@ -2,7 +2,8 @@
 
 /datum/controller/subsystem/icon_cache
 	name = "Icon Cache"
-	flags = SS_NO_FIRE | SS_NO_INIT
+	flags = SS_NO_FIRE
+	init_order = SS_INIT_MISC_FIRST
 
 	// Cached bloody overlays, key is object type.
 	var/list/bloody_cache = list()
@@ -67,9 +68,20 @@
 
 	var/list/rgb_blend_cache = list()	// not an icon per-se, but this proc could be expensive so we might as well cache it.
 
+	var/list/space_dust_cache = list()
+
+	var/list/space_cache = list()
+
 /datum/controller/subsystem/icon_cache/New()
 	NEW_SS_GLOBAL(SSicon_cache)
 
+/datum/controller/subsystem/icon_cache/Initialize()
+	build_dust_cache()
+	build_space_cache()
+	setup_collar_mappings()
+	setup_uniform_mappings()
+	..()
+
 /datum/controller/subsystem/icon_cache/proc/setup_collar_mappings()
 	collar_states = list()
 	for (var/i in icon_states('icons/mob/collar.dmi'))
@@ -94,3 +106,20 @@
 	var/image/I = new(icon, icon_state)
 	I.color = color
 	return I
+
+/datum/controller/subsystem/icon_cache/proc/build_dust_cache()
+	for (var/i in 0 to 25)
+		var/image/im = image('icons/turf/space_parallax1.dmi',"[i]")
+		im.plane = PLANE_SPACE_DUST
+		im.alpha = 80
+		im.blend_mode = BLEND_ADD
+		space_dust_cache["[i]"] = im
+
+/datum/controller/subsystem/icon_cache/proc/build_space_cache()
+	for (var/i in 0 to 25)
+		var/image/I = new()
+		I.appearance = /turf/space
+		var/istr = "[i]"
+		I.icon_state = istr
+		I.overlays += space_dust_cache[istr]
+		space_cache[istr] = I

code/controllers/subsystems/icon_smooth.dm

@@ -8,6 +8,7 @@ var/datum/controller/subsystem/icon_smooth/SSicon_smooth
 	flags = SS_TICKER | SS_FIRE_IN_LOBBY
 
 	var/list/smooth_queue = list()
+	var/list/typecachecache = list()
 
 	var/explosion_in_progress = FALSE
 

code/controllers/subsystems/overlays.dm

@@ -102,25 +102,33 @@ var/datum/controller/subsystem/overlays/SSoverlays
 		. = iconbro.appearance
 		icon_cache[icon] = .
 
-/atom/proc/build_appearance_list(new_overlays)
-	var/static/image/appearance_bro = new()
-	if (!islist(new_overlays))
-		new_overlays = list(new_overlays)
-	else
-		listclearnulls(new_overlays)
-	for (var/i in 1 to length(new_overlays))
-		var/image/cached_overlay = new_overlays[i]
-		if (istext(cached_overlay))
-			new_overlays[i] = iconstate2appearance(icon, cached_overlay)
-		else if(isicon(cached_overlay))
-			new_overlays[i] = icon2appearance(cached_overlay)
-		else	//image probable
-			appearance_bro.appearance = cached_overlay
-			if(!ispath(cached_overlay))
-				appearance_bro.dir = cached_overlay.dir
-			new_overlays[i] = appearance_bro.appearance
-	return new_overlays
+#define APPEARANCEIFY(origin, target) \
+	if (istext(origin)) { \
+		target = iconstate2appearance(icon, origin); \
+	} \
+	else if (isicon(origin)) { \
+		target = icon2appearance(origin); \
+	} \
+	else { \
+		appearance_bro.appearance = origin; \
+		if (!ispath(origin)) { \
+			appearance_bro.dir = origin.dir; \
+		} \
+		target = appearance_bro.appearance; \
+	}
 
+/atom/proc/build_appearance_list(atom/new_overlays)
+	var/static/image/appearance_bro = new
+	if (islist(new_overlays))
+		listclearnulls(new_overlays)
+		for (var/i in 1 to length(new_overlays))
+			var/image/cached_overlay = new_overlays[i]
+			APPEARANCEIFY(cached_overlay, new_overlays[i])
+		return new_overlays
+	else
+		APPEARANCEIFY(new_overlays, .)
+
+#undef APPEARANCEIFY
 #define NOT_QUEUED_ALREADY (!(overlay_queued))
 #define QUEUE_FOR_COMPILE overlay_queued = TRUE; SSoverlays.processing += src;
 
@@ -165,7 +173,7 @@ var/datum/controller/subsystem/overlays/SSoverlays
 
 	overlays = build_appearance_list(overlays)
 
-	if (!overlays.len)
+	if (!overlays || (islist(overlays) && !overlays.len))
 		// No point trying to compile if we don't have any overlays.
 		return