oh fucking boy

code/modules/atmospherics/environmental/LINDA_turf_tile.dm

@@ -90,6 +90,7 @@
 
 /turf/open/archive()
 	ARCHIVE_TEMPERATURE(air)
+	air.gases_archived = air.gases.Copy()
 	archived_cycle = SSair.times_fired
 	temperature_archived = temperature
 

code/modules/atmospherics/gasmixtures/gas_mixture.dm

@@ -15,15 +15,16 @@ GLOBAL_LIST_INIT(meta_gas_overlays, meta_gas_overlay_list())
 GLOBAL_LIST_INIT(meta_gas_dangers, meta_gas_danger_list())
 GLOBAL_LIST_INIT(meta_gas_ids, meta_gas_id_list())
 GLOBAL_LIST_INIT(meta_gas_fusions, meta_gas_fusion_list())
+
 /datum/gas_mixture
 	var/list/gases = list()
+	var/tmp/list/gases_archived = list()
 	var/temperature = 0 //kelvins
 	var/tmp/temperature_archived = 0
 	var/volume = CELL_VOLUME //liters
 	var/last_share = 0
 	var/list/reaction_results = list()
 	var/list/analyzer_results //used for analyzer feedback - not initialized until its used
-	var/gc_share = FALSE // Whether to call garbage_collect() on the sharer during shares, used for immutable mixtures
 
 /datum/gas_mixture/New(volume)
 	if (!isnull(volume))
@@ -219,7 +220,7 @@ GLOBAL_LIST_INIT(meta_gas_fusions, meta_gas_fusion_list())
 
 /datum/gas_mixture/share(datum/gas_mixture/sharer, atmos_adjacent_turfs = 4)
 
-	var/list/cached_gases = gases
+	var/list/cached_gases = gases_archived
 	var/list/sharer_gases = sharer.gases
 
 	var/temperature_delta = temperature_archived - sharer.temperature_archived
@@ -242,10 +243,28 @@ GLOBAL_LIST_INIT(meta_gas_fusions, meta_gas_fusion_list())
 	var/gas_heat_capacity
 	//and also cache this shit rq because that results in sanic speed for reasons byond explanation
 	var/list/cached_gasheats = GLOB.meta_gas_specific_heats
+
+	//Do this early and save doing TWO MORE (probable) LIST ACCESSES!!
+	var/our_moles
+	var/their_moles
+
+	//decs are expensive
+	var/us
+	var/them
+
 	//GAS TRANSFER
 	for(var/id in cached_gases | sharer_gases) // transfer gases
+		us = cached_gases[id]
+		them = sharer_gases[id]
 
-		delta = QUANTIZE(cached_gases[id] - sharer_gases[id])/(atmos_adjacent_turfs+1) //the amount of gas that gets moved between the mixtures
+		//buitl in garbage collect
+		if(max(us, them) <= ATMOS_QUANTIZATION_ACCURACY)
+			cached_gases -= id
+			sharer_gases -= id
+			continue
+
+		delta = QUANTIZE(us - them)/(atmos_adjacent_turfs+1) //the amount of gas that gets moved between the mixtures
+		our_moles += cached
 
 		if(delta && abs_temperature_delta > MINIMUM_TEMPERATURE_DELTA_TO_CONSIDER)
 			gas_heat_capacity = delta * cached_gasheats[id]
@@ -259,6 +278,9 @@ GLOBAL_LIST_INIT(meta_gas_fusions, meta_gas_fusion_list())
 		moved_moles			+= delta
 		abs_moved_moles		+= abs(delta)
 
+		our_moles += cached_gases[id]
+		their_moles += sharer_gases[id]
+
 	last_share = abs_moved_moles
 
 	//THERMAL ENERGY TRANSFER
@@ -278,13 +300,7 @@ GLOBAL_LIST_INIT(meta_gas_fusions, meta_gas_fusion_list())
 				if(abs(new_sharer_heat_capacity/old_sharer_heat_capacity - 1) < 0.1) // <10% change in sharer heat capacity
 					temperature_share(sharer, OPEN_HEAT_TRANSFER_COEFFICIENT)
 
-	if (initial(sharer.gc_share))
-		GAS_GARBAGE_COLLECT(sharer.gases)
 	if(temperature_delta > MINIMUM_TEMPERATURE_TO_MOVE || abs(moved_moles) > MINIMUM_MOLES_DELTA_TO_MOVE)
-		var/our_moles
-		TOTAL_MOLES(cached_gases,our_moles)
-		var/their_moles
-		TOTAL_MOLES(sharer_gases,their_moles)
 		return (temperature_archived*(our_moles + moved_moles) - sharer.temperature_archived*(their_moles - moved_moles)) * R_IDEAL_GAS_EQUATION / volume
 
 /datum/gas_mixture/temperature_share(datum/gas_mixture/sharer, conduction_coefficient, sharer_temperature, sharer_heat_capacity)

code/modules/atmospherics/gasmixtures/immutable_mixtures.dm

@@ -3,7 +3,6 @@
 
 /datum/gas_mixture/immutable
 	var/initial_temperature
-	gc_share = TRUE
 
 /datum/gas_mixture/immutable/New()
 	..()