diff --git a/smartline/display.lua b/smartline/display.lua
index 6ae1f93..61fb9d5 100644
--- a/smartline/display.lua
+++ b/smartline/display.lua
@@ -27,6 +27,11 @@ function display_update(pos, objref)
 							visual_size = {x=0.94, y=0.94} })
 end
 
+local function on_timer(pos)
+	local meta = minetest.get_meta(pos)
+	display_lib.update_entities(pos)
+	return false
+end
 
 local lcd_box = {
 	type = "wallmounted",
@@ -59,6 +64,7 @@ minetest.register_node("smartline:display", {
 		display_lib.update_entities(pos)
 	end,
 
+	on_timer = on_timer,
 	on_place = display_lib.on_place,
 	on_construct = display_lib.on_construct,
 	on_destruct = display_lib.on_destruct,
@@ -121,18 +127,25 @@ end
 tubelib.register_node("smartline:display", {}, {
 	on_recv_message = function(pos, topic, payload)
 		local node = minetest.get_node(pos)
+		local timer = minetest.get_node_timer(pos)
 		if topic == "text" then  -- add one line and scroll if necessary
 			local meta = minetest.get_meta(pos)
 			add_line(meta, payload)
-			display_lib.update_entities(pos)
+			if not timer:is_started() then
+				timer:start(2)
+			end
 		elseif topic == "row" then  -- overwrite the given row
 			local meta = minetest.get_meta(pos)
 			write_row(meta, payload)
-			display_lib.update_entities(pos)
+			if not timer:is_started() then
+				timer:start(2)
+			end
 		elseif topic == "clear" then  -- clear the screen
 			local meta = minetest.get_meta(pos)
 			meta:set_string("text", "")
-			display_lib.update_entities(pos)
+			if not timer:is_started() then
+				timer:start(2)
+			end
 		end
 	end,
 })		
diff --git a/tubelib/command.lua b/tubelib/command.lua
index 933281b..5415ebe 100644
--- a/tubelib/command.lua
+++ b/tubelib/command.lua
@@ -94,6 +94,20 @@ local function generate_Key2Number()
 	end
 end
 
+local function not_protected(pos, placer_name, clicker_name)
+	local meta = minetest.get_meta(pos)
+	if meta then
+		local cached_name = meta:get_string("tubelib_cached_name")
+		if placer_name and (placer_name == cached_name or not minetest.is_protected(pos, placer_name)) then
+			meta:set_string("tubelib_cached_name", placer_name)
+			if clicker_name == nil or not minetest.is_protected(pos, clicker_name) then
+				return true
+			end
+		end
+	end
+	return false
+end
+
 -------------------------------------------------------------------
 -- API helper functions
 -------------------------------------------------------------------
@@ -224,11 +238,9 @@ function tubelib.send_message(numbers, placer_name, clicker_name, topic, payload
 	for _,num in ipairs(string_split(numbers, " ")) do
 		if Number2Pos[num] and Number2Pos[num].name then
 			local data = Number2Pos[num]
-			if placer_name and not minetest.is_protected(data.pos, placer_name) then
-				if clicker_name == nil or not minetest.is_protected(data.pos, clicker_name) then
-					if tubelib_NodeDef[data.name] and tubelib_NodeDef[data.name].on_recv_message then
-						tubelib_NodeDef[data.name].on_recv_message(data.pos, topic, payload)
-					end
+			if not_protected(data.pos, placer_name, clicker_name) then
+				if tubelib_NodeDef[data.name] and tubelib_NodeDef[data.name].on_recv_message then
+					tubelib_NodeDef[data.name].on_recv_message(data.pos, topic, payload)
 				end
 			end
 		end