do not use minetest.find_node_near, I guess it's a bit laggy

moremesecons_jammer/init.lua

@@ -1,5 +1,41 @@
 local JAMMER_MAX_DISTANCE = 10
 
+-- see wireless jammer
+local get = vector.get_data_from_pos
+local set = vector.set_data_to_pos
+local remove = vector.remove_data_from_pos
+
+local jammers = {}
+local function add_jammer(pos)
+	if get(jammers, pos.z,pos.y,pos.x) then
+		return
+	end
+	set(jammers, pos.z,pos.y,pos.x, true)
+end
+
+local function remove_jammer(pos)
+	remove(jammers, pos.z,pos.y,pos.x)
+end
+
+local function is_jammed(pos)
+	local pz,py,px = vector.unpack(pos)
+	for z,yxs in pairs(jammers) do
+		if math.abs(pz-z) <= JAMMER_MAX_DISTANCE then
+			for y,xs in pairs(yxs) do
+				if math.abs(py-y) <= JAMMER_MAX_DISTANCE then
+					for x in pairs(xs) do
+						if math.abs(px-x) <= JAMMER_MAX_DISTANCE
+						and (px-x)^2+(py-y)^2+(pz-z)^2 <= JAMMER_MAX_DISTANCE^2 then
+							return true
+						end
+					end
+				end
+			end
+		end
+	end
+	return false
+end
+
 minetest.after(0, function() -- After load all mods
 	function mesecon.turnon(pos, link) -- Overwrite mesecons function.
 		local frontiers = {{pos = pos, link = link}}
@@ -12,8 +48,8 @@ function mesecon.turnon(pos, link) -- Overwrite mesecons function.
 			-- area not loaded, postpone action
 			if not node then
 				mesecon.queue:add_action(f.pos, "turnon", {link}, nil, true)
-		elseif minetest.find_node_near(f.pos, JAMMER_MAX_DISTANCE, {"moremesecons_jammer:jammer_on"}) then -- JAMMER
-			break
+			elseif is_jammed(f.pos) then -- JAMMER
+				return
 			elseif mesecon.is_conductor_off(node, f.link) then
 				local rules = mesecon.conductor_get_rules(node)
 
@@ -54,15 +90,21 @@ mesecon.register_node("moremesecons_jammer:jammer", {
 	groups = {dig_immediate=2},
 	mesecons = {effector = {
 		action_on = function(pos)
+			add_jammer(pos)
 			minetest.swap_node(pos, {name="moremesecons_jammer:jammer_on"})
-		end }}
+		end
+	}},
 },{
 	tiles = {"moremesecons_jammer_on.png"},
 	groups = {dig_immediate=2, not_in_creative_inventory=1},
 	mesecons = {effector = {
 		action_off = function(pos)
+			remove_jammer(pos)
 			minetest.swap_node(pos, {name="moremesecons_jammer:jammer_off"})
-		end }}
+		end
+	}},
+	on_destruct = remove_jammer,
+	on_construct = add_jammer,
 })
 
 minetest.register_craft({
@@ -70,3 +112,10 @@ minetest.register_craft({
 	recipe = {{"group:mesecon_conductor_craftable", "default:mese", "group:mesecon_conductor_craftable"},
 		{"", "moremesecons_wireless:jammer_off", ""}}
 })
+
+minetest.register_abm({
+	nodenames = {"moremesecons_jammer:jammer_on"},
+	interval = 5,
+	chance = 1,
+	action = add_jammer
+})