diff --git a/scada-common/util.lua b/scada-common/util.lua
index b311511..97afdfd 100644
--- a/scada-common/util.lua
+++ b/scada-common/util.lua
@@ -4,6 +4,16 @@
 
 local cc_strings = require("cc.strings")
 
+local math = math
+local string = string
+local table = table
+local os = os
+
+local getmetatable = getmetatable
+local print = print
+local tostring = tostring
+local type = type
+
 ---@class util
 local util = {}
 
@@ -29,6 +39,8 @@ end
 
 --#region PRINT
 
+local p_time = "[%H:%M:%S] "
+
 -- print
 ---@param message any
 function util.print(message) term.write(tostring(message)) end
@@ -39,11 +51,11 @@ function util.println(message) print(tostring(message)) end
 
 -- timestamped print
 ---@param message any
-function util.print_ts(message) term.write(os.date("[%H:%M:%S] ") .. tostring(message)) end
+function util.print_ts(message) term.write(os.date(p_time) .. tostring(message)) end
 
 -- timestamped print line
 ---@param message any
-function util.println_ts(message) print(os.date("[%H:%M:%S] ") .. tostring(message)) end
+function util.println_ts(message) print(os.date(p_time) .. tostring(message)) end
 
 --#endregion
 
@@ -54,10 +66,9 @@ function util.println_ts(message) print(os.date("[%H:%M:%S] ") .. tostring(messa
 ---@param val any
 ---@return string
 function util.strval(val)
-    local t = type(val)
     -- this depends on Lua short-circuiting the or check for metatables (note: metatables won't have metatables)
-    if (t == "table" and (getmetatable(val) == nil or getmetatable(val).__tostring == nil)) or t == "function" then
-        return "[" .. tostring(val) .. "]"
+    if (util.is_tbl(val) and (getmetatable(val) == nil or getmetatable(val).__tostring == nil)) or util.is_func(val) then
+        return table.concat{"[", tostring(val), "]"}
     else return tostring(val) end
 end
 
@@ -77,7 +88,7 @@ function util.pad(str, n)
     local lpad = math.floor((n - len) / 2)
     local rpad = (n - len) - lpad
 
-    return util.spaces(lpad) .. str .. util.spaces(rpad)
+    return table.concat{util.spaces(lpad), str, util.spaces(rpad)}
 end
 
 -- wrap a string into a table of lines
@@ -95,9 +106,9 @@ function util.strwrap(str, limit) return cc_strings.wrap(str, limit) end
 ---@return string
 ---@diagnostic disable-next-line: unused-vararg
 function util.concat(...)
-    local str = ""
-    for _, v in ipairs(arg) do str = str .. util.strval(v) end
-    return str
+    local strings = {}
+    for i = 1, #arg do strings[i] = util.strval(arg[i]) end
+    return table.concat(strings)
 end
 
 -- alias
@@ -112,6 +123,9 @@ function util.sprintf(format, ...) return string.format(format, table.unpack(arg
 
 -- luacheck: unused args
 
+local gsub_p_a, gsub_r_a = "^(%s-%d+)(%d%d%d)", "%1,%2"
+local gsub_p_b, gsub_r_b = " %s-", ""
+
 -- format a number string with commas as the thousands separator<br>
 -- subtracts from spaces at the start if present for each comma used
 ---@nodiscard
@@ -123,11 +137,11 @@ function util.comma_format(num)
     local i = 1
 
     while i > 0 do
-        formatted, i = formatted:gsub("^(%s-%d+)(%d%d%d)", '%1,%2')
+        formatted, i = formatted:gsub(gsub_p_a, gsub_r_a)
         if i > 0 then commas = commas + 1 end
     end
 
-    local _, num_spaces = formatted:gsub(" %s-", "")
+    local _, num_spaces = formatted:gsub(gsub_p_b, gsub_r_b)
     local remove = math.min(num_spaces, commas)
 
     formatted = string.sub(formatted, remove + 1)
@@ -157,7 +171,7 @@ function util.round(x) return math.floor(x + 0.5) end
 function util.mov_avg(length, default)
     local data = {}
     local index = 1
-    local last_t = 0    ---@type number|nil
+    local last_t = 0 ---@type number|nil
 
     ---@class moving_average
     local public = {}
@@ -173,9 +187,7 @@ function util.mov_avg(length, default)
     ---@param x number new value
     ---@param t number? optional last update time to prevent duplicated entries
     function public.record(x, t)
-        if type(t) == "number" and last_t == t then
-            return
-        end
+        if util.is_num(t) and last_t == t then return end
 
         data[index] = x
         last_t = t
@@ -202,61 +214,62 @@ end
 
 --#region TYPES
 
+-- for speed
+local b_str, n_str, s_str, t_str, f_str = "boolean", "number", "string", "table", "function"
+
 -- is a value a boolean
 ---@nodiscard
 ---@param x any value
 ---@return boolean is_boolean
-function util.is_bool(x) return type(x) == "boolean" end
+function util.is_bool(x) return type(x) == b_str end
 
 -- is a value a number
 ---@nodiscard
 ---@param x any value
 ---@return boolean is_number
-function util.is_num(x) return type(x) == "number" end
+function util.is_num(x) return type(x) == n_str end
 
 -- is a value an integer
 ---@nodiscard
 ---@param x any value
 ---@return boolean is_integer
-function util.is_int(x) return type(x) == "number" and x == math.floor(x) end
+function util.is_int(x) return type(x) == n_str and x == math.floor(x) end
 
 -- is a value a string
 ---@nodiscard
 ---@param x any value
 ---@return boolean is_string
-function util.is_str(x) return type(x) == "string" end
+function util.is_str(x) return type(x) == s_str end
 
 -- is a value a table
 ---@nodiscard
 ---@param x any value
 ---@return boolean is_table
-function util.is_tbl(x) return type(x) == "table" end
+function util.is_tbl(x) return type(x) == t_str end
 
 -- is a value a function
 ---@nodiscard
 ---@param x any value
 ---@return boolean is_function
-function util.is_func(x) return type(x) == "function" end
+function util.is_func(x) return type(x) == f_str end
 
 --#endregion
 
 --#region TIME
 
+local t_l = "local"
+
 -- current time
 ---@nodiscard
 ---@return integer milliseconds
-function util.time_ms()
 ---@diagnostic disable-next-line: undefined-field
-    return os.epoch('local')
-end
+function util.time_ms() return os.epoch(t_l) end
 
 -- current time
 ---@nodiscard
 ---@return number seconds
-function util.time_s()
 ---@diagnostic disable-next-line: undefined-field
-    return os.epoch('local') / 1000.0
-end
+function util.time_s() return os.epoch(t_l) / 1000.0 end
 
 -- current time
 ---@nodiscard
@@ -271,10 +284,8 @@ function util.time() return util.time_ms() end
 ---@nodiscard
 ---@param target_event? string event to wait for
 ---@return os_event event, any param1, any param2, any param3, any param4, any param5
-function util.pull_event(target_event)
 ---@diagnostic disable-next-line: undefined-field
-    return os.pullEventRaw(target_event)
-end
+function util.pull_event(target_event) return os.pullEventRaw(target_event) end
 
 -- OS queue event raw wrapper with types
 ---@param event os_event
@@ -292,17 +303,13 @@ end
 ---@nodiscard
 ---@param t number timer duration in seconds
 ---@return integer timer ID
-function util.start_timer(t)
 ---@diagnostic disable-next-line: undefined-field
-    return os.startTimer(t)
-end
+function util.start_timer(t) return os.startTimer(t) end
 
 -- cancel an OS timer
 ---@param timer integer timer ID
-function util.cancel_timer(timer)
 ---@diagnostic disable-next-line: undefined-field
-    os.cancelTimer(timer)
-end
+function util.cancel_timer(timer) os.cancelTimer(timer) end
 
 --#endregion
 
@@ -311,10 +318,8 @@ end
 -- protected sleep call so we still are in charge of catching termination
 ---@param t integer seconds
 --- EVENT_CONSUMER: this function consumes events
-function util.psleep(t)
 ---@diagnostic disable-next-line: undefined-field
-    pcall(os.sleep, t)
-end
+function util.psleep(t) pcall(os.sleep, t) end
 
 -- no-op to provide a brief pause (1 tick) to yield<br>
 --- EVENT_CONSUMER: this function consumes events
@@ -405,8 +410,7 @@ local function ZFE(fe) return fe / 1000000000000000000000.0 end -- how & why did
 ---@param format? string format override
 ---@return string str, string? unit
 function util.power_format(fe, combine_label, format)
-    local unit
-    local value
+    local unit, value
 
     if type(format) ~= "string" then format = "%.2f" end
 
@@ -454,32 +458,25 @@ end
 ---@nodiscard
 ---@param timeout number timeout duration
 function util.new_watchdog(timeout)
-    local self = {
-        timeout = timeout,
-        wd_timer = util.start_timer(timeout)
-    }
+    local self = { timeout = timeout, wd_timer = util.start_timer(timeout) }
 
     ---@class watchdog
     local public = {}
 
     -- check if a timer is this watchdog
     ---@nodiscard
-    ---@param timer number timer event timer ID
+    ---@param timer number event timer ID
     function public.is_timer(timer) return self.wd_timer == timer end
 
     -- satiate the beast
     function public.feed()
-        if self.wd_timer ~= nil then
-            util.cancel_timer(self.wd_timer)
-        end
+        public.cancel()
         self.wd_timer = util.start_timer(self.timeout)
     end
 
     -- cancel the watchdog
     function public.cancel()
-        if self.wd_timer ~= nil then
-            util.cancel_timer(self.wd_timer)
-        end
+        if self.wd_timer ~= nil then util.cancel_timer(self.wd_timer) end
     end
 
     return public
@@ -492,10 +489,7 @@ end
 ---@nodiscard
 ---@param period number clock period
 function util.new_clock(period)
-    local self = {
-        period = period,
-        timer = nil
-    }
+    local self = { period = period, timer = nil }
 
     ---@class clock
     local public = {}