Asset Cache speed (tgstation/tgstation#35003 + more)

code/controllers/master_controller.dm

@@ -55,17 +55,10 @@ var/global/pipe_processing_killed = 0
 
 	space_manager.do_transition_setup()
 
-	setup_asset_cache()
 	setupfactions()
 	setup_economy()
 
 	for(var/i=0, i<max_secret_rooms, i++)
 		make_mining_asteroid_secret()
 
-	populate_spawn_points()
-
-/datum/controller/game_controller/proc/setup_asset_cache()
-	var/watch = start_watch()
-	log_startup_progress("Populating asset cache...")
-	populate_asset_cache()
-	log_startup_progress("	Populated [asset_cache.len] assets in [stop_watch(watch)]s.")
+	populate_spawn_points()

code/controllers/subsystem/assets.dm

@@ -0,0 +1,17 @@
+SUBSYSTEM_DEF(assets)
+	name = "Assets"
+	init_order = INIT_ORDER_ASSETS
+	flags = SS_NO_FIRE
+	var/list/cache = list()
+	var/list/preload = list()
+
+/datum/controller/subsystem/assets/Initialize(timeofday)
+	for(var/type in typesof(/datum/asset) - list(/datum/asset, /datum/asset/simple))
+		var/datum/asset/A = new type()
+		A.register()
+
+	preload = cache.Copy() //don't preload assets generated during the round
+
+	for(var/client/C in GLOB.clients)
+		addtimer(CALLBACK(GLOBAL_PROC, .proc/getFilesSlow, C, preload, FALSE), 10)
+	..()