diff --git a/cart_entity.lua b/cart_entity.lua
index 3edbede..0105cf5 100644
--- a/cart_entity.lua
+++ b/cart_entity.lua
@@ -1,17 +1,17 @@
 
 local HAVE_MESECONS_ENABLED = minetest.global_exists("mesecon")
 
-function boost_cart:on_rail_step(pos)
+function boost_cart:on_rail_step(entity, pos, distance)
 	-- Play rail sound
-	if self.sound_counter <= 0 then
+	if entity.sound_counter <= 0 then
 		minetest.sound_play("cart_rail", {
 			pos = pos,
 			max_hear_distance = 40,
 			gain = 0.5
 		})
-		self.sound_counter = math.random(4, 15)
+		entity.sound_counter = math.random(4, 15)
 	end
-	self.sound_counter = self.sound_counter - 1
+	entity.sound_counter = entity.sound_counter - distance
 
 	if HAVE_MESECONS_ENABLED then
 		boost_cart:signal_detector_rail(pos)
@@ -65,7 +65,7 @@ function cart_entity:on_activate(staticdata, dtime_s)
 		return
 	end
 	local data = minetest.deserialize(staticdata)
-	if not data or type(data) ~= "table" then
+	if type(data) ~= "table" then
 		return
 	end
 	self.railtype = data.railtype
@@ -149,6 +149,7 @@ function cart_entity:on_punch(puncher, time_from_last_punch, tool_capabilities,
 	self.punched = true
 end
 
+local v3_len = vector.length
 function cart_entity:on_step(dtime)
 	local vel = self.object:get_velocity()
 	if self.punched then
@@ -161,10 +162,10 @@ function cart_entity:on_step(dtime)
 
 	local pos = self.object:get_pos()
 	local cart_dir = boost_cart:velocity_to_dir(vel)
+	local same_dir = vector.equals(cart_dir, self.old_dir)
 	local update = {}
 
-	if self.old_pos and not self.punched
-			and vector.equals(cart_dir, self.old_dir) then
+	if self.old_pos and not self.punched and same_dir then
 		local flo_pos = vector.round(pos)
 		local flo_old = vector.round(self.old_pos)
 		if vector.equals(flo_pos, flo_old) then
@@ -174,6 +175,7 @@ function cart_entity:on_step(dtime)
 	end
 
 	local ctrl, player
+	local distance = 1
 
 	-- Get player controls
 	if self.driver then
@@ -184,12 +186,11 @@ function cart_entity:on_step(dtime)
 	end
 
 	local stop_wiggle = false
-	if self.old_pos and vector.equals(cart_dir, self.old_dir) then
+	if self.old_pos and same_dir then
 		-- Detection for "skipping" nodes (perhaps use average dtime?)
 		-- It's sophisticated enough to take the acceleration in account
 		local acc = self.object:get_acceleration()
-		local distance = dtime * (vector.length(vel) +
-			0.5 * dtime * vector.length(acc))
+		distance = dtime * (v3_len(vel) + 0.5 * dtime * v3_len(acc))
 
 		local new_pos, new_dir = boost_cart:pathfinder(
 			pos, self.old_pos, self.old_dir, distance, ctrl,
@@ -230,7 +231,7 @@ function cart_entity:on_step(dtime)
 	else
 		-- Direction change detected
 		if not vector.equals(dir, self.old_dir) then
-			vel = vector.multiply(dir, vector.length(vel))
+			vel = vector.multiply(dir, v3_len(vel))
 			update.vel = true
 			if dir.y ~= self.old_dir.y then
 				pos = vector.round(pos)
@@ -293,7 +294,6 @@ function cart_entity:on_step(dtime)
 
 		new_acc = vector.multiply(dir, acc)
 	end
-	boost_cart.on_rail_step(self, vector.round(pos))
 
 	-- Limits
 	local max_vel = boost_cart.speed_max
@@ -312,6 +312,7 @@ function cart_entity:on_step(dtime)
 	end
 	self.old_switch = switch_keys
 
+	boost_cart:on_rail_step(self, self.old_pos, distance)
 
 	if self.punched then
 		-- Collect dropped items
diff --git a/functions.lua b/functions.lua
index 13b6087..86de036 100644
--- a/functions.lua
+++ b/functions.lua
@@ -30,14 +30,16 @@ end
 
 function boost_cart:velocity_to_dir(v)
 	if math.abs(v.x) > math.abs(v.z) then
-		return {x=boost_cart:get_sign(v.x), y=boost_cart:get_sign(v.y), z=0}
+		return {x=self:get_sign(v.x), y=self:get_sign(v.y), z=0}
 	else
-		return {x=0, y=boost_cart:get_sign(v.y), z=boost_cart:get_sign(v.z)}
+		return {x=0, y=self:get_sign(v.y), z=self:get_sign(v.z)}
 	end
 end
 
+local get_node = minetest.get_node
+local get_item_group = minetest.get_item_group
 function boost_cart:is_rail(pos, railtype)
-	local node = minetest.get_node(pos).name
+	local node = get_node(pos).name
 	if node == "ignore" then
 		local vm = minetest.get_voxel_manip()
 		local emin, emax = vm:read_from_map(pos, pos)
@@ -49,13 +51,13 @@ function boost_cart:is_rail(pos, railtype)
 		local vi = area:indexp(pos)
 		node = minetest.get_name_from_content_id(data[vi])
 	end
-	if minetest.get_item_group(node, "rail") == 0 then
+	if get_item_group(node, "rail") == 0 then
 		return false
 	end
 	if not railtype then
 		return true
 	end
-	return minetest.get_item_group(node, "connect_to_raillike") == railtype
+	return get_item_group(node, "connect_to_raillike") == railtype
 end
 
 function boost_cart:check_front_up_down(pos, dir_, check_up, railtype)
@@ -65,21 +67,21 @@ function boost_cart:check_front_up_down(pos, dir_, check_up, railtype)
 	-- Front
 	dir.y = 0
 	cur = vector.add(pos, dir)
-	if boost_cart:is_rail(cur, railtype) then
+	if self:is_rail(cur, railtype) then
 		return dir
 	end
 	-- Up
 	if check_up then
 		dir.y = 1
 		cur = vector.add(pos, dir)
-		if boost_cart:is_rail(cur, railtype) then
+		if self:is_rail(cur, railtype) then
 			return dir
 		end
 	end
 	-- Down
 	dir.y = -1
 	cur = vector.add(pos, dir)
-	if boost_cart:is_rail(cur, railtype) then
+	if self:is_rail(cur, railtype) then
 		return dir
 	end
 	return nil
@@ -108,14 +110,14 @@ function boost_cart:get_rail_direction(pos_, dir, ctrl, old_switch, railtype)
 			right_check = false
 		end
 		if ctrl.left and left_check then
-			cur = boost_cart:check_front_up_down(pos, left, false, railtype)
+			cur = self:check_front_up_down(pos, left, false, railtype)
 			if cur then
 				return cur, 1
 			end
 			left_check = false
 		end
 		if ctrl.right and right_check then
-			cur = boost_cart:check_front_up_down(pos, right, false, railtype)
+			cur = self:check_front_up_down(pos, right, false, railtype)
 			if cur then
 				return cur, 2
 			end
@@ -124,14 +126,14 @@ function boost_cart:get_rail_direction(pos_, dir, ctrl, old_switch, railtype)
 	end
 
 	-- Normal
-	cur = boost_cart:check_front_up_down(pos, dir, true, railtype)
+	cur = self:check_front_up_down(pos, dir, true, railtype)
 	if cur then
 		return cur
 	end
 
 	-- Left, if not already checked
 	if left_check then
-		cur = boost_cart:check_front_up_down(pos, left, false, railtype)
+		cur = self:check_front_up_down(pos, left, false, railtype)
 		if cur then
 			return cur
 		end
@@ -139,7 +141,7 @@ function boost_cart:get_rail_direction(pos_, dir, ctrl, old_switch, railtype)
 
 	-- Right, if not already checked
 	if right_check then
-		cur = boost_cart:check_front_up_down(pos, right, false, railtype)
+		cur = self:check_front_up_down(pos, right, false, railtype)
 		if cur then
 			return cur
 		end
@@ -147,7 +149,7 @@ function boost_cart:get_rail_direction(pos_, dir, ctrl, old_switch, railtype)
 
 	-- Backwards
 	if not old_switch then
-		cur = boost_cart:check_front_up_down(pos, {
+		cur = self:check_front_up_down(pos, {
 				x = -dir.x,
 				y = dir.y,
 				z = -dir.z
@@ -174,7 +176,7 @@ function boost_cart:pathfinder(pos_, old_pos, old_dir, distance, ctrl,
 		math.floor(distance + 1))
 
 	for i = 1, distance do
-		pf_dir, pf_switch = boost_cart:get_rail_direction(
+		pf_dir, pf_switch = self:get_rail_direction(
 			pf_pos, pf_dir, ctrl, pf_switch, railtype)
 
 		if vector.equals(pf_dir, {x=0, y=0, z=0}) then