[MIRROR] Fixes Massive Radio Overtime, Implements a Spatial Grid System for Faster Searching Over Areas [MDB IGNORE] (#10107)

* Fixes Massive Radio Overtime, Implements a Spatial Grid System for Faster Searching Over Areas

* no spamming pings for upstream :(

* E

* E

Co-authored-by: Kylerace <kylerlumpkin1@gmail.com>
Co-authored-by: GoldenAlpharex <58045821+GoldenAlpharex@users.noreply.github.com>
Co-authored-by: Gandalf <jzo123@hotmail.com>

code/modules/client/client_defines.dm

@@ -164,6 +164,7 @@
 
 	var/list/parallax_layers
 	var/list/parallax_layers_cached
+	///this is the last recorded client eye by SSparallax/fire()
 	var/atom/movable/movingmob
 	var/turf/previous_turf
 	///world.time of when we can state animate()ing parallax again

code/modules/client/client_procs.dm

@@ -536,10 +536,11 @@ GLOBAL_LIST_INIT(blacklisted_builds, list(
 
 			send2adminchat("Server", "[cheesy_message] (No admins online)")
 	QDEL_LIST_ASSOC_VAL(char_render_holders)
+
 	if(movingmob != null)
-		movingmob.client_mobs_in_contents -= mob
-		UNSETEMPTY(movingmob.client_mobs_in_contents)
+		LAZYREMOVE(movingmob.client_mobs_in_contents, mob)
 		movingmob = null
+
 	active_mousedown_item = null
 	SSambience.remove_ambience_client(src)
 	QDEL_NULL(view_size)