diff --git a/code/controllers/subsystems/tgui.dm b/code/controllers/subsystems/tgui.dm
index eb0d566f4b..73494cbf46 100644
--- a/code/controllers/subsystems/tgui.dm
+++ b/code/controllers/subsystems/tgui.dm
@@ -1,12 +1,16 @@
- /**
-  * tgui subsystem
-  *
-  * Contains all tgui state and subsystem code.
- **/
-
+/*!
+ * Copyright (c) 2020 Aleksej Komarov
+ * SPDX-License-Identifier: MIT
+ */
+/**
+ * tgui subsystem
+ *
+ * Contains all tgui state and subsystem code.
+ *
+ */
 
 SUBSYSTEM_DEF(tgui)
-	name = "TGUI"
+	name = "tgui"
 	wait = 9
 	flags = SS_NO_INIT
 	priority = FIRE_PRIORITY_TGUI
@@ -14,10 +18,8 @@ SUBSYSTEM_DEF(tgui)
 
 	/// A list of UIs scheduled to process
 	var/list/current_run = list()
-	/// A list of open UIs
-	var/list/open_uis = list()
-	/// A list of open UIs, grouped by src_object and ui_key.
-	var/list/open_uis_by_src = list()
+	/// A list of all open UIs
+	var/list/all_uis = list()
 	/// The HTML base used for all UIs.
 	var/basehtml
 
@@ -33,11 +35,11 @@ SUBSYSTEM_DEF(tgui)
 	close_all_uis()
 
 /datum/controller/subsystem/tgui/stat_entry()
-	..("P:[open_uis.len]")
+	..("P:[all_uis.len]")
 
 /datum/controller/subsystem/tgui/fire(resumed = 0)
 	if(!resumed)
-		src.current_run = open_uis.Copy()
+		src.current_run = all_uis.Copy()
 	// Cache for sanic speed (lists are references anyways)
 	var/list/current_run = src.current_run
 	while(current_run.len)
@@ -47,7 +49,7 @@ SUBSYSTEM_DEF(tgui)
 		if(ui && ui.user && ui.src_object)
 			ui.process()
 		else
-			open_uis.Remove(ui)
+			ui.close(0)
 		if(MC_TICK_CHECK)
 			return
 
@@ -162,11 +164,10 @@ SUBSYSTEM_DEF(tgui)
   * return datum/tgui The found UI.
  **/
 /datum/controller/subsystem/tgui/proc/get_open_ui(mob/user, datum/src_object)
-	var/key = "[REF(src_object)]"
 	// No UIs opened for this src_object
-	if(isnull(open_uis_by_src[key]) || !istype(open_uis_by_src[key], /list))
-		return null // No UIs open.
-	for(var/datum/tgui/ui in open_uis_by_src[key]) // Find UIs for this object.
+	if(!LAZYLEN(src_object?.open_tguis))
+		return null
+	for(var/datum/tgui/ui in src_object.open_tguis)
 		// Make sure we have the right user
 		if(ui.user == user)
 			return ui
@@ -182,14 +183,14 @@ SUBSYSTEM_DEF(tgui)
   * return int The number of UIs updated.
  **/
 /datum/controller/subsystem/tgui/proc/update_uis(datum/src_object)
+	// No UIs opened for this src_object
+	if(!LAZYLEN(src_object?.open_tguis))
+		return 0
 	var/count = 0
-	var/key = "[REF(src_object)]"
-	if(isnull(open_uis_by_src[key]) || !istype(open_uis_by_src[key], /list))
-		return count // Couldn't find any UIs for this object.
-	for(var/datum/tgui/ui in open_uis_by_src[key])
+	for(var/datum/tgui/ui in src_object.open_tguis)
 		// Check the UI is valid.
 		if(ui && ui.src_object && ui.user && ui.src_object.tgui_host(ui.user))
-			ui.process(force = 1) // Update the UI.
+			INVOKE_ASYNC(ui, TYPE_PROC_REF(/datum/tgui, process), wait * 0.1, TRUE)
 			count++ // Count each UI we update.
 	return count
 
@@ -203,12 +204,11 @@ SUBSYSTEM_DEF(tgui)
   * return int The number of UIs closed.
  **/
 /datum/controller/subsystem/tgui/proc/close_uis(datum/src_object)
-	var/count = 0
-	var/key = "[REF(src_object)]"
 	// No UIs opened for this src_object
-	if(isnull(open_uis_by_src[key]) || !istype(open_uis_by_src[key], /list))
-		return count
-	for(var/datum/tgui/ui in open_uis_by_src[key])
+	if(!LAZYLEN(src_object?.open_tguis))
+		return 0
+	var/count = 0
+	for(var/datum/tgui/ui in src_object.open_tguis)
 		if(ui && ui.src_object && ui.user && ui.src_object.tgui_host(ui.user)) // Check the UI is valid.
 			ui.close() // Close the UI.
 			count++ // Count each UI we close.
@@ -223,11 +223,11 @@ SUBSYSTEM_DEF(tgui)
  **/
 /datum/controller/subsystem/tgui/proc/close_all_uis()
 	var/count = 0
-	for(var/key in open_uis_by_src)
-		for(var/datum/tgui/ui in open_uis_by_src[key])
-			if(ui && ui.src_object && ui.user && ui.src_object.tgui_host(ui.user)) // Check the UI is valid.
-				ui.close() // Close the UI.
-				count++ // Count each UI we close.
+	for(var/datum/tgui/ui in all_uis)
+		// Check if UI is valid.
+		if(ui?.src_object && ui.user && ui.src_object.tgui_host(ui.user))
+			ui.close()
+			count++
 	return count
 
  /**
@@ -278,13 +278,9 @@ SUBSYSTEM_DEF(tgui)
   * required ui datum/tgui The UI to be added.
  **/
 /datum/controller/subsystem/tgui/proc/on_open(datum/tgui/ui)
-	var/key = "[REF(ui.src_object)]"
-	if(isnull(open_uis_by_src[key]) || !istype(open_uis_by_src[key], /list))
-		open_uis_by_src[key] = list()
-	ui.user.tgui_open_uis |= ui
-	var/list/uis = open_uis_by_src[key]
-	uis |= ui
-	open_uis |= ui
+	ui.user?.tgui_open_uis |= ui
+	LAZYOR(ui.src_object.open_tguis, ui)
+	all_uis |= ui
 
  /**
   * private
@@ -296,18 +292,14 @@ SUBSYSTEM_DEF(tgui)
   * return bool If the UI was removed or not.
  **/
 /datum/controller/subsystem/tgui/proc/on_close(datum/tgui/ui)
-	var/key = "[REF(ui.src_object)]"
-	if(isnull(open_uis_by_src[key]) || !istype(open_uis_by_src[key], /list))
-		return FALSE
 	// Remove it from the list of processing UIs.
-	open_uis.Remove(ui)
+	all_uis -= ui
+	current_run -= ui
 	// If the user exists, remove it from them too.
 	if(ui.user)
-		ui.user.tgui_open_uis.Remove(ui)
-	var/list/uis = open_uis_by_src[key]
-	uis.Remove(ui)
-	if(length(uis) == 0)
-		open_uis_by_src.Remove(key)
+		ui.user.tgui_open_uis -= ui
+	if(ui.src_object)
+		LAZYREMOVE(ui.src_object.open_tguis, ui)
 	return TRUE
 
  /**
@@ -342,7 +334,7 @@ SUBSYSTEM_DEF(tgui)
 	for(var/datum/tgui/ui in source.tgui_open_uis)
 		// Inform the UIs of their new owner.
 		ui.user = target
-		target.tgui_open_uis.Add(ui)
+		target.tgui_open_uis += ui
 	// Clear the old list.
 	source.tgui_open_uis.Cut()
 	return TRUE
diff --git a/code/datums/datum.dm b/code/datums/datum.dm
index 4e3fd10a08..624dfa70df 100644
--- a/code/datums/datum.dm
+++ b/code/datums/datum.dm
@@ -17,6 +17,10 @@
 	  */
 	var/gc_destroyed
 
+	/// Open uis owned by this datum
+	/// Lazy, since this case is semi rare
+	var/list/open_tguis // CHOMPEdit: FIXME: open_uis
+
 	/// Active timers with this datum as the target
 	var/list/active_timers
 
diff --git a/code/modules/tgui/tgui.dm b/code/modules/tgui/tgui.dm
index 5c39c756ad..cf75db176c 100644
--- a/code/modules/tgui/tgui.dm
+++ b/code/modules/tgui/tgui.dm
@@ -253,7 +253,6 @@
 		),
 		"user" = list(
 			"name" = "[user]",
-			"ckey" = "[user.ckey]",
 			"observer" = isobserver(user),
 		),
 	)