hopefully a performance improvement to stop genitalia from having to update everytime.

code/__DEFINES/inventory.dm

@@ -237,3 +237,6 @@ GLOBAL_LIST_INIT(security_wintercoat_allowed, typecacheof(list(
 
 //Internals checker
 #define GET_INTERNAL_SLOTS(C) list(C.head, C.wear_mask)
+
+//Slots that won't trigger humans' update_genitals() on equip().
+GLOBAL_LIST_INIT(no_genitals_update_slots, list(SLOT_L_STORE, SLOT_R_STORE, SLOT_S_STORE, SLOT_IN_BACKPACK, SLOT_LEGCUFFED, SLOT_HANDCUFFED, SLOT_HANDS, SLOT_GENERC_DEXTROUS_STORAGE))

code/modules/mob/living/carbon/human/inventory.dm

@@ -79,7 +79,8 @@
 
 //This is an UNSAFE proc. Use mob_can_equip() before calling this one! Or rather use equip_to_slot_if_possible() or advanced_equip_to_slot_if_possible()
 /mob/living/carbon/human/equip_to_slot(obj/item/I, slot)
-	if(!..()) //a check failed or the item has already found its slot
+	. = ..()
+	if(!.) //a check failed or the item has already found its slot
 		return
 
 	var/not_handled = FALSE //Added in case we make this type path deeper one day
@@ -136,6 +137,7 @@
 			update_inv_s_store()
 		else
 			to_chat(src, "<span class='danger'>You are trying to equip this item to an unsupported inventory slot. Report this to a coder!</span>")
+			not_handled = TRUE
 
 	//Item is handled and in slot, valid to call callback, for this proc should always be true
 	if(!not_handled)

modular_citadel/code/modules/arousal/genitals.dm

@@ -209,11 +209,10 @@
 
 //procs to handle sprite overlays being applied to humans
 
-/obj/item/equipped(mob/user, slot)
-	if(ishuman(user))
-		var/mob/living/carbon/human/H = user
-		H.update_genitals()
+/mob/living/carbon/human/equip_to_slot(obj/item/I, slot)
 	. = ..()
+	if(!. && !(slot in GLOB.no_genitals_update_slots)) //the item was successfully equipped, and the chosen slot wasn't merely storage or hands.
+		update_genitals()
 
 /mob/living/carbon/human/doUnEquip(obj/item/I, force)
 	. = ..()