Fixes #9211

Instead of several minutes long spawn, blood is added to processing for drying out now. Processing proc itself is just compraing two vars so shouldn't be as bad.
This way it doesn't get referenced by unnamed proc and can be qdel'd properly.

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

@@ -20,10 +20,12 @@ var/global/list/image/splatter_cache=list()
 	var/basecolor="#A10808" // Color when wet.
 	var/list/datum/disease2/disease/virus2 = list()
 	var/amount = 5
+	var/drytime
 
 /obj/effect/decal/cleanable/blood/Destroy()
 	for(var/datum/disease/D in viruses)
 		D.cure(0)
+	processing_objects -= src
 	return ..()
 
 /obj/effect/decal/cleanable/blood/New()
@@ -38,7 +40,11 @@ var/global/list/image/splatter_cache=list()
 					if (B.blood_DNA)
 						blood_DNA |= B.blood_DNA.Copy()
 					qdel(B)
-	spawn(DRYING_TIME * (amount+1))
+	drytime = world.time + DRYING_TIME * (amount+1)
+	processing_objects += src
+
+/obj/effect/decal/cleanable/blood/process()
+	if(world.time > drytime)
 		dry()
 
 /obj/effect/decal/cleanable/blood/update_icon()
@@ -91,6 +97,7 @@ var/global/list/image/splatter_cache=list()
 	desc = drydesc
 	color = adjust_brightness(color, -50)
 	amount = 0
+	processing_objects -= src
 
 /obj/effect/decal/cleanable/blood/attack_hand(mob/living/carbon/human/user)
 	..()
@@ -125,8 +132,7 @@ var/global/list/image/splatter_cache=list()
 
 /obj/effect/decal/cleanable/blood/drip/New()
 	..()
-	spawn(1)
-		drips |= icon_state
+	drips |= icon_state
 
 /obj/effect/decal/cleanable/blood/writing
 	icon_state = "tracks"