This should hopefully reduce processing requirements, by not rebuilding icons every tick.

(Ported oldcode, all props to Strumpetplaya)

code/game/objects/items/weapons/cigs_lighters.dm

@@ -266,6 +266,7 @@ ZIPPO
 				else
 					user.r_hand = W
 				W.layer = 20
+				user.update_clothing()
 		else
 			return ..()
 		src.update_icon()

code/game/objects/items/weapons/dna_injector.dm

@@ -87,6 +87,7 @@
 
 			spawn( 0 )
 				O.process()
+				user.update_clothing()
 				return
 		else
 			for(var/mob/O in viewers(M, null))

code/game/objects/items/weapons/implants/implantfreedom.dm

@@ -29,6 +29,7 @@
 					dropped(source)
 					if (W)
 						W.layer = initial(W.layer)
+				source.update_clothing()
 		return