While learning from third party's Lua code, I found at the top of the main script file
local insert = table.insert
local match = string.match
local gsub = string.gsub
I understand these chunks as shortcut definitions, but I also found
local assert = assert
local ipairs = ipairs
local print = print
What is the purpose of these last instructions ?
Accessing locals is faster. So in some cases it might make sense to make frequently used things local to save a few percent of processing time. But in most cases there you can save yourself the trouble. Especially if a global isn't used thousands of times.
Give this a read:
Why are local variables accessed faster than global variables in lua?
It increase a little bit performance in some workload
reason why: Why are localized functions faster in Lua?