diff --git a/byond-extools.dll b/byond-extools.dll
new file mode 100644
index 0000000000..a83ea1e543
Binary files /dev/null and b/byond-extools.dll differ
diff --git a/code/__DEFINES/_tick.dm b/code/__DEFINES/_tick.dm
index 10b815e547..fc6147c430 100644
--- a/code/__DEFINES/_tick.dm
+++ b/code/__DEFINES/_tick.dm
@@ -1,13 +1,28 @@
-#define TICK_LIMIT_RUNNING 80
+/// Percentage of tick to leave for master controller to run
+#define MAPTICK_MC_MIN_RESERVE 70
+/// internal_tick_usage is updated every tick by extools
+#define MAPTICK_LAST_INTERNAL_TICK_USAGE ((GLOB.internal_tick_usage / world.tick_lag) * 100)
+/// Tick limit while running normally
+#define TICK_BYOND_RESERVE 2
+#define TICK_LIMIT_RUNNING (max(100 - TICK_BYOND_RESERVE - MAPTICK_LAST_INTERNAL_TICK_USAGE, MAPTICK_MC_MIN_RESERVE))
+/// Tick limit used to resume things in stoplag
 #define TICK_LIMIT_TO_RUN 70
+/// Tick limit for MC while running
 #define TICK_LIMIT_MC 70
-#define TICK_LIMIT_MC_INIT_DEFAULT 98
+/// Tick limit while initializing
+#define TICK_LIMIT_MC_INIT_DEFAULT (100 - TICK_BYOND_RESERVE)
 
-#define TICK_USAGE world.tick_usage //for general usage
-#define TICK_USAGE_REAL world.tick_usage    //to be used where the result isn't checked
+/// for general usage of tick_usage
+#define TICK_USAGE world.tick_usage
+/// to be used where the result isn't checked
+#define TICK_USAGE_REAL world.tick_usage
 
+/// Returns true if tick_usage is above the limit
 #define TICK_CHECK ( TICK_USAGE > Master.current_ticklimit )
+/// runs stoplag if tick_usage is above the limit
 #define CHECK_TICK ( TICK_CHECK ? stoplag() : 0 )
 
+/// Returns true if tick usage is above 95, for high priority usage
 #define TICK_CHECK_HIGH_PRIORITY ( TICK_USAGE > 95 )
+/// runs stoplag if tick_usage is above 95, for high priority usage
 #define CHECK_TICK_HIGH_PRIORITY ( TICK_CHECK_HIGH_PRIORITY? stoplag() : 0 )
diff --git a/code/__DEFINES/subsystems.dm b/code/__DEFINES/subsystems.dm
index cadc1113c5..3abef3a61c 100644
--- a/code/__DEFINES/subsystems.dm
+++ b/code/__DEFINES/subsystems.dm
@@ -132,8 +132,15 @@
 
 #define RUNLEVELS_DEFAULT (RUNLEVEL_SETUP | RUNLEVEL_GAME | RUNLEVEL_POSTGAME)
 
-
-
+// SSair run section
+#define SSAIR_PIPENETS 1
+#define SSAIR_ATMOSMACHINERY 2
+#define SSAIR_REACTQUEUE 3
+#define SSAIR_EXCITEDGROUPS 4
+#define SSAIR_HIGHPRESSURE 5
+#define SSAIR_HOTSPOTS 6
+#define SSAIR_SUPERCONDUCTIVITY 7
+#define SSAIR_REBUILD_PIPENETS 8
 
 #define COMPILE_OVERLAYS(A)\
 	if (TRUE) {\
diff --git a/code/_globalvars/misc.dm b/code/_globalvars/misc.dm
index af483bf888..b039e6d114 100644
--- a/code/_globalvars/misc.dm
+++ b/code/_globalvars/misc.dm
@@ -33,3 +33,5 @@ GLOBAL_VAR(bible_icon_state)
 GLOBAL_VAR(bible_item_state)
 GLOBAL_VAR(holy_weapon_type)
 GLOBAL_VAR(holy_armor_type)
+
+GLOBAL_VAR_INIT(internal_tick_usage, 0.2 * world.tick_lag)
diff --git a/code/controllers/master.dm b/code/controllers/master.dm
index 8772fac5af..db828539af 100644
--- a/code/controllers/master.dm
+++ b/code/controllers/master.dm
@@ -36,6 +36,9 @@ GLOBAL_REAL(Master, /datum/controller/master) = new
 
 	var/sleep_delta = 1
 
+	///Only run ticker subsystems for the next n ticks.
+	var/skip_ticks = 0
+
 	var/make_runtime = 0
 
 	var/initializations_finished_with_no_players_logged_in	//I wonder what this could be?
@@ -335,7 +338,7 @@ GLOBAL_REAL(Master, /datum/controller/master) = new
 			new/datum/controller/failsafe() // (re)Start the failsafe.
 
 		//now do the actual stuff
-		if (!queue_head || !(iteration % 3))
+		if (!skip_ticks)
 			var/checking_runlevel = current_runlevel
 			if(cached_runlevel != checking_runlevel)
 				//resechedule subsystems
@@ -381,6 +384,8 @@ GLOBAL_REAL(Master, /datum/controller/master) = new
 
 		iteration++
 		last_run = world.time
+		if (skip_ticks)
+			skip_ticks--
 		src.sleep_delta = MC_AVERAGE_FAST(src.sleep_delta, sleep_delta)
 		current_ticklimit = TICK_LIMIT_RUNNING
 		if (processing * sleep_delta <= world.tick_lag)
@@ -444,10 +449,12 @@ GLOBAL_REAL(Master, /datum/controller/master) = new
 		while (queue_node)
 			if (ran && TICK_USAGE > TICK_LIMIT_RUNNING)
 				break
-
 			queue_node_flags = queue_node.flags
 			queue_node_priority = queue_node.queued_priority
 
+			if (!(queue_node_flags & SS_TICKER) && skip_ticks)
+				queue_node = queue_node.queue_next
+				continue
 			//super special case, subsystems where we can't make them pause mid way through
 			//if we can't run them this tick (without going over a tick)
 			//we bump up their priority and attempt to run them next tick
@@ -455,14 +462,15 @@ GLOBAL_REAL(Master, /datum/controller/master) = new
 			//	in those cases, so we just let them run)
 			if (queue_node_flags & SS_NO_TICK_CHECK)
 				if (queue_node.tick_usage > TICK_LIMIT_RUNNING - TICK_USAGE && ran_non_ticker)
-					queue_node.queued_priority += queue_priority_count * 0.1
-					queue_priority_count -= queue_node_priority
-					queue_priority_count += queue_node.queued_priority
-					current_tick_budget -= queue_node_priority
-					queue_node = queue_node.queue_next
+					if (!(queue_node_flags & SS_BACKGROUND))
+						queue_node.queued_priority += queue_priority_count * 0.1
+						queue_priority_count -= queue_node_priority
+						queue_priority_count += queue_node.queued_priority
+						current_tick_budget -= queue_node_priority
+						queue_node = queue_node.queue_next
 					continue
 
-			if ((queue_node_flags & SS_BACKGROUND) && !bg_calc)
+			if (!bg_calc && (queue_node_flags & SS_BACKGROUND))
 				current_tick_budget = queue_priority_count_bg
 				bg_calc = TRUE
 
@@ -515,7 +523,7 @@ GLOBAL_REAL(Master, /datum/controller/master) = new
 			queue_node.paused_ticks = 0
 			queue_node.paused_tick_usage = 0
 
-			if (queue_node_flags & SS_BACKGROUND) //update our running total
+			if (bg_calc) //update our running total
 				queue_priority_count_bg -= queue_node_priority
 			else
 				queue_priority_count -= queue_node_priority
@@ -583,14 +591,19 @@ GLOBAL_REAL(Master, /datum/controller/master) = new
 	log_world("MC: SoftReset: Finished.")
 	. = 1
 
+/// Warns us that the end of tick byond map_update will be laggier then normal, so that we can just skip running subsystems this tick.
+/datum/controller/master/proc/laggy_byond_map_update_incoming()
+	if (!skip_ticks)
+		skip_ticks = 1
 
 
 /datum/controller/master/stat_entry()
 	if(!statclick)
 		statclick = new/obj/effect/statclick/debug(null, "Initializing...", src)
 
-	stat("Byond:", "(FPS:[world.fps]) (TickCount:[world.time/world.tick_lag]) (TickDrift:[round(Master.tickdrift,1)]([round((Master.tickdrift/(world.time/world.tick_lag))*100,0.1)]%))")
-	stat("Master Controller:", statclick.update("(TickRate:[Master.processing]) (Iteration:[Master.iteration])"))
+	stat("Byond:", "(FPS:[world.fps]) (TickCount:[world.time/world.tick_lag]) (TickDrift:[round(Master.tickdrift,1)]([round((Master.tickdrift/(world.time/world.tick_lag))*100,0.1)]%)) (Internal Tick Usage: [round(MAPTICK_LAST_INTERNAL_TICK_USAGE,0.1)]%)")
+	stat("Master Controller:", statclick.update("(TickRate:[Master.processing]) (Iteration:[Master.iteration]) (TickLimit: [round(Master.current_ticklimit, 0.1)])"))
+
 
 /datum/controller/master/StartLoadingMap()
 	//disallow more than one map to load at once, multithreading it will just cause race conditions
diff --git a/code/controllers/subsystem/air.dm b/code/controllers/subsystem/air.dm
index 13facc7666..d8c7724333 100644
--- a/code/controllers/subsystem/air.dm
+++ b/code/controllers/subsystem/air.dm
@@ -1,11 +1,3 @@
-#define SSAIR_PIPENETS 1
-#define SSAIR_ATMOSMACHINERY 2
-#define SSAIR_REACTQUEUE 3
-#define SSAIR_EXCITEDGROUPS 4
-#define SSAIR_HIGHPRESSURE 5
-#define SSAIR_HOTSPOTS 6
-#define SSAIR_SUPERCONDUCTIVITY 7
-
 SUBSYSTEM_DEF(air)
 	name = "Atmospherics"
 	init_order = INIT_ORDER_AIR
@@ -20,6 +12,7 @@ SUBSYSTEM_DEF(air)
 	var/cost_hotspots = 0
 	var/cost_superconductivity = 0
 	var/cost_pipenets = 0
+	var/cost_rebuilds = 0
 	var/cost_atmos_machinery = 0
 
 	var/list/excited_groups = list()
@@ -27,6 +20,7 @@ SUBSYSTEM_DEF(air)
 	var/list/turf_react_queue = list()
 	var/list/hotspots = list()
 	var/list/networks = list()
+	var/list/pipenets_needing_rebuilt = list()
 	var/list/obj/machinery/atmos_machinery = list()
 	var/list/pipe_init_dirs_cache = list()
 
@@ -39,7 +33,7 @@ SUBSYSTEM_DEF(air)
 
 
 	var/list/currentrun = list()
-	var/currentpart = SSAIR_PIPENETS
+	var/currentpart = SSAIR_REBUILD_PIPENETS
 
 	var/map_loading = TRUE
 	var/list/queued_for_activation
@@ -52,6 +46,7 @@ SUBSYSTEM_DEF(air)
 	msg += "HS:[round(cost_hotspots,1)]|"
 	msg += "SC:[round(cost_superconductivity,1)]|"
 	msg += "PN:[round(cost_pipenets,1)]|"
+	msg += "RB:[round(cost_rebuilds,1)]|"
 	msg += "AM:[round(cost_atmos_machinery,1)]"
 	msg += "} "
 	msg += "AT:[active_turfs.len]|"
@@ -77,6 +72,18 @@ SUBSYSTEM_DEF(air)
 /datum/controller/subsystem/air/fire(resumed = 0)
 	var/timer = TICK_USAGE_REAL
 
+	if(currentpart == SSAIR_REBUILD_PIPENETS)
+		var/list/pipenet_rebuilds = pipenets_needing_rebuilt
+		for(var/thing in pipenet_rebuilds)
+			var/obj/machinery/atmospherics/AT = thing
+			AT.build_network()
+		cost_rebuilds = MC_AVERAGE(cost_rebuilds, TICK_DELTA_TO_MS(TICK_USAGE_REAL - timer))
+		pipenets_needing_rebuilt.Cut()
+		if(state != SS_RUNNING)
+			return
+		resumed = FALSE
+		currentpart = SSAIR_PIPENETS
+
 	if(currentpart == SSAIR_PIPENETS || !resumed)
 		process_pipenets(resumed)
 		cost_pipenets = MC_AVERAGE(cost_pipenets, TICK_DELTA_TO_MS(TICK_USAGE_REAL - timer))
@@ -137,9 +144,7 @@ SUBSYSTEM_DEF(air)
 		if(state != SS_RUNNING)
 			return
 		resumed = 0
-	currentpart = SSAIR_PIPENETS
-
-
+	currentpart = SSAIR_REBUILD_PIPENETS
 
 /datum/controller/subsystem/air/proc/process_pipenets(resumed = 0)
 	if (!resumed)
@@ -156,6 +161,9 @@ SUBSYSTEM_DEF(air)
 		if(MC_TICK_CHECK)
 			return
 
+/datum/controller/subsystem/air/proc/add_to_rebuild_queue(atmos_machine)
+	if(istype(atmos_machine, /obj/machinery/atmospherics))
+		pipenets_needing_rebuilt += atmos_machine
 
 /datum/controller/subsystem/air/proc/process_atmos_machinery(resumed = 0)
 	var/seconds = wait * 0.1
diff --git a/code/game/world.dm b/code/game/world.dm
index 1d719ee138..94cfb0baca 100644
--- a/code/game/world.dm
+++ b/code/game/world.dm
@@ -8,6 +8,8 @@ GLOBAL_LIST(topic_status_cache)
 //This happens after the Master subsystem new(s) (it's a global datum)
 //So subsystems globals exist, but are not initialised
 /world/New()
+	if(fexists("byond-extools.dll"))
+		call("byond-extools.dll", "maptick_initialize")()
 	enable_debugger()
 
 	world.Profile(PROFILE_START)
diff --git a/code/modules/atmospherics/machinery/atmosmachinery.dm b/code/modules/atmospherics/machinery/atmosmachinery.dm
index 864edfdbe6..8f5ab7dd5e 100644
--- a/code/modules/atmospherics/machinery/atmosmachinery.dm
+++ b/code/modules/atmospherics/machinery/atmosmachinery.dm
@@ -64,6 +64,7 @@
 		nullifyNode(i)
 
 	SSair.atmos_machinery -= src
+	SSair.pipenets_needing_rebuilt -= src
 
 	dropContents()
 	if(pipe_vision_img)
diff --git a/code/modules/atmospherics/machinery/components/binary_devices/circulator.dm b/code/modules/atmospherics/machinery/components/binary_devices/circulator.dm
index 73cb8eeecb..c164dc5ae3 100644
--- a/code/modules/atmospherics/machinery/components/binary_devices/circulator.dm
+++ b/code/modules/atmospherics/machinery/components/binary_devices/circulator.dm
@@ -116,7 +116,7 @@
 		if(node2)
 			node2.atmosinit()
 			node2.addMember(src)
-		build_network()
+		SSair.add_to_rebuild_queue(src)
 
 	return TRUE
 
diff --git a/code/modules/atmospherics/machinery/components/components_base.dm b/code/modules/atmospherics/machinery/components/components_base.dm
index 63a03b1d40..a45728d51f 100644
--- a/code/modules/atmospherics/machinery/components/components_base.dm
+++ b/code/modules/atmospherics/machinery/components/components_base.dm
@@ -144,7 +144,7 @@
 		var/datum/pipeline/parent = parents[i]
 		if(!parent)
 			stack_trace("Component is missing a pipenet! Rebuilding...")
-			build_network()
+			SSair.add_to_rebuild_queue(src)
 		parent.update = 1
 
 /obj/machinery/atmospherics/components/returnPipenets()
diff --git a/code/modules/atmospherics/machinery/components/unary_devices/cryo.dm b/code/modules/atmospherics/machinery/components/unary_devices/cryo.dm
index e013a86fd2..38042fe64d 100644
--- a/code/modules/atmospherics/machinery/components/unary_devices/cryo.dm
+++ b/code/modules/atmospherics/machinery/components/unary_devices/cryo.dm
@@ -447,6 +447,6 @@
 		if(node)
 			node.atmosinit()
 			node.addMember(src)
-		build_network()
+		SSair.add_to_rebuild_queue(src)
 
 #undef CRYOMOBS
diff --git a/code/modules/atmospherics/machinery/components/unary_devices/thermomachine.dm b/code/modules/atmospherics/machinery/components/unary_devices/thermomachine.dm
index dbe3c0b90b..dddfdf08c1 100644
--- a/code/modules/atmospherics/machinery/components/unary_devices/thermomachine.dm
+++ b/code/modules/atmospherics/machinery/components/unary_devices/thermomachine.dm
@@ -116,7 +116,7 @@
 	if(node)
 		node.atmosinit()
 		node.addMember(src)
-	build_network()
+	SSair.add_to_rebuild_queue(src)
 	return TRUE
 
 /obj/machinery/atmospherics/components/unary/thermomachine/ui_status(mob/user)
diff --git a/code/modules/atmospherics/machinery/pipes/layermanifold.dm b/code/modules/atmospherics/machinery/pipes/layermanifold.dm
index 33092f5354..bc8fd6777d 100644
--- a/code/modules/atmospherics/machinery/pipes/layermanifold.dm
+++ b/code/modules/atmospherics/machinery/pipes/layermanifold.dm
@@ -31,7 +31,7 @@
 	nodes = list()
 	for(var/obj/machinery/atmospherics/A in needs_nullifying)
 		A.disconnect(src)
-		A.build_network()
+		SSair.add_to_rebuild_queue(A)
 
 /obj/machinery/atmospherics/pipe/layer_manifold/proc/get_all_connected_nodes()
 	return front_nodes + back_nodes + nodes
diff --git a/code/modules/atmospherics/machinery/pipes/pipes.dm b/code/modules/atmospherics/machinery/pipes/pipes.dm
index 1e513b846c..c466a422b2 100644
--- a/code/modules/atmospherics/machinery/pipes/pipes.dm
+++ b/code/modules/atmospherics/machinery/pipes/pipes.dm
@@ -22,7 +22,7 @@
 	var/obj/machinery/atmospherics/oldN = nodes[i]
 	..()
 	if(oldN)
-		oldN.build_network()
+		SSair.add_to_rebuild_queue(oldN)
 
 /obj/machinery/atmospherics/pipe/destroy_network()
 	QDEL_NULL(parent)
diff --git a/code/modules/atmospherics/machinery/portable/canister.dm b/code/modules/atmospherics/machinery/portable/canister.dm
index a41bdee3b6..03463ff0f7 100644
--- a/code/modules/atmospherics/machinery/portable/canister.dm
+++ b/code/modules/atmospherics/machinery/portable/canister.dm
@@ -159,7 +159,6 @@
 /obj/machinery/portable_atmospherics/canister/proto
 	name = "prototype canister"
 
-
 /obj/machinery/portable_atmospherics/canister/proto/default
 	name = "prototype canister"
 	desc = "The best way to fix an atmospheric emergency... or the best way to introduce one."
@@ -172,7 +171,6 @@
 	can_min_release_pressure = (ONE_ATMOSPHERE / 30)
 	prototype = TRUE
 
-
 /obj/machinery/portable_atmospherics/canister/proto/default/oxygen
 	name = "prototype canister"
 	desc = "A prototype canister for a prototype bike, what could go wrong?"
@@ -181,8 +179,6 @@
 	filled = 1
 	release_pressure = ONE_ATMOSPHERE*2
 
-
-
 /obj/machinery/portable_atmospherics/canister/New(loc, datum/gas_mixture/existing_mixture)
 	..()
 	if(existing_mixture)
@@ -192,7 +188,7 @@
 	pump = new(src, FALSE)
 	pump.on = TRUE
 	pump.stat = 0
-	pump.build_network()
+	SSair.add_to_rebuild_queue(pump)
 
 	update_icon()
 
@@ -208,6 +204,7 @@
 		air_contents.gases[gas_type] = (maximum_pressure * filled) * air_contents.volume / (R_IDEAL_GAS_EQUATION * air_contents.temperature)
 		if(starter_temp)
 			air_contents.temperature = starter_temp
+
 /obj/machinery/portable_atmospherics/canister/air/create_gas()
 	air_contents.gases[/datum/gas/oxygen] = (O2STANDARD * maximum_pressure * filled) * air_contents.volume / (R_IDEAL_GAS_EQUATION * air_contents.temperature)
 	air_contents.gases[/datum/gas/nitrogen] = (N2STANDARD * maximum_pressure * filled) * air_contents.volume / (R_IDEAL_GAS_EQUATION * air_contents.temperature)
diff --git a/code/modules/atmospherics/machinery/portable/pump.dm b/code/modules/atmospherics/machinery/portable/pump.dm
index 18e4da621a..377e9285e3 100644
--- a/code/modules/atmospherics/machinery/portable/pump.dm
+++ b/code/modules/atmospherics/machinery/portable/pump.dm
@@ -20,7 +20,7 @@
 	pump = new(src, FALSE)
 	pump.on = TRUE
 	pump.stat = 0
-	pump.build_network()
+	SSair.add_to_rebuild_queue(pump)
 
 /obj/machinery/portable_atmospherics/pump/Destroy()
 	var/turf/T = get_turf(src)
diff --git a/code/modules/shuttle/on_move.dm b/code/modules/shuttle/on_move.dm
index 701c153783..8c1b3fa955 100644
--- a/code/modules/shuttle/on_move.dm
+++ b/code/modules/shuttle/on_move.dm
@@ -249,7 +249,7 @@ All ShuttleMove procs go here
 			A.atmosinit()
 			if(A.returnPipenet())
 				A.addMember(src)
-		build_network()
+		SSair.add_to_rebuild_queue(src)
 	else
 		// atmosinit() calls update_icon(), so we don't need to call it
 		update_icon()