Ported tg asset cache

code/controllers/subsystems/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)
+	return ..()

code/controllers/subsystems/nanoui.dm

@@ -24,7 +24,7 @@ SUBSYSTEM_DEF(nanoui)
 		for(var/filename in filenames)
 			if(copytext(filename, length(filename)) != "/") // filenames which end in "/" are actually directories, which we want to ignore
 				if(fexists(path + filename))
-					asset_files.Add(fcopy_rsc(path + filename)) // add this file to asset_files for sending to clients when they connect
+					asset_files[filename] = fcopy_rsc(path + filename) // add this file to asset_files for sending to clients when they connect
 	.=..()
 	for(var/i in GLOB.clients)
 		send_resources(i)
@@ -49,5 +49,4 @@ SUBSYSTEM_DEF(nanoui)
 /datum/controller/subsystem/nanoui/proc/send_resources(client)
 	if(!subsystem_initialized)
 		return
-	for(var/file in asset_files)
-		client << browse_rsc(file)	// send the file to the client
+	getFilesSlow(client, asset_files)