Some quick tips for lua performance:
Always create local references to methods within tables if they are going to be called many times.
The example here is using tables. Put this at the top of your lua file, and this will improve perf if you are operating on tables many times in a frame.
local tinsert = table.insert
local tremove = table.remove
local tconcat = table.concat
You can do this with any module or lua script table you are using.