Minor Performance Tweaks (#3265)

changes:

/datum/wires no longer has an (init) proc.
SMES wires now use timers instead of spawn.
Cleanables' random_icon_states list is now lazy. (eliminates ~4000 lists from dirt)
/obj/effect can no longer be pushed around by conveyor belts.
Lighting overlays are now explicitly prevented from being moved by conveyor belts.

code/game/objects/effects/decals/Cleanable/humans.dm

@@ -142,11 +142,11 @@
 	icon_state = "1"
 	random_icon_states = list("1","2","3","4","5")
 	amount = 0
-	var/list/drips = list()
+	var/list/drips
 
 /obj/effect/decal/cleanable/blood/drip/Initialize()
 	. = ..()
-	drips |= icon_state
+	drips = list(icon_state)
 
 /obj/effect/decal/cleanable/blood/writing
 	icon_state = "tracks"
@@ -158,9 +158,9 @@
 
 /obj/effect/decal/cleanable/blood/writing/Initialize()
 	. = ..()
-	if(random_icon_states.len)
+	if(LAZYLEN(random_icon_states))
 		for(var/obj/effect/decal/cleanable/blood/writing/W in loc)
-			random_icon_states.Remove(W.icon_state)
+			random_icon_states -= W.icon_state
 		icon_state = pick(random_icon_states)
 	else
 		icon_state = "writing1"
@@ -193,8 +193,8 @@
 	blood.Blend(basecolor,ICON_MULTIPLY)
 
 	icon = blood
-	overlays.Cut()
-	overlays += giblets
+	cut_overlays()
+	add_overlay(giblets)
 
 /obj/effect/decal/cleanable/blood/gibs/up
 	random_icon_states = list("gib1", "gib2", "gib3", "gib4", "gib5", "gib6","gibup1","gibup1","gibup1")
@@ -238,7 +238,7 @@
 	layer = 2
 	icon = 'icons/effects/blood.dmi'
 	icon_state = "mucus"
-	random_icon_states = list("mucus")
+	random_icon_states = null
 
 	var/list/datum/disease2/disease/virus2 = list()
 	var/dry = 0 // Keeps the lag down

code/game/objects/effects/decals/cleanable.dm

@@ -1,5 +1,5 @@
 /obj/effect/decal/cleanable
-	var/list/random_icon_states = list()
+	var/list/random_icon_states
 
 /obj/effect/decal/cleanable/clean_blood(var/ignore = 0)
 	if(!ignore)
@@ -7,7 +7,7 @@
 		return
 	..()
 
-/obj/effect/decal/cleanable/New()
-	if (random_icon_states && length(src.random_icon_states) > 0)
-		src.icon_state = pick(src.random_icon_states)
-	..()
+/obj/effect/decal/cleanable/Initialize()
+	if (LAZYLEN(random_icon_states))
+		icon_state = pick(src.random_icon_states)
+	. = ..()