[[https://www.lua.org/gems/sample.pdf|Lua Performance Tips]]
[[https://stackoverflow.com/questions/154672/what-can-i-do-to-increase-the-performance-of-a-lua-program|What can I do to increase the performance of a Lua program?]]
 
====== Avoid globals ======
Local variables are very fast as they reside in virtual machine registers, and are accessed directly by index. Global variables on the other hand, reside in a lua table and as such are accessed by a hash lookup." -- Thomas Jefferson

<code lua>
local find = string.find
local sin = math.sin
</code>

====== Use table preallocation ======
Inserting element to table requires reallocation.
For small  tables better is to preallocate:
<code lua>
local t = { 0, 0, 0, 0, 0 } -- allocate 5 element table
</code>

====== Avoid creating tables or closures in loops ======
Creating or extending table requires heap allocation. 

====== Use short inline instad of function calls ======
Also true for LUAJit:
<code lua>
t[#t+1] = 0 is faster than table.insert(t, 0). 
</code>

====== Avoid new string creation ======

Lua hashes all strings on creation, this makes comparison and using them in tables very fast and reduces memory use since all strings are stored internally only once. But it makes string creation more expensive.
<code lua>
local ret = {};
for i=1, C do
  ret[#ret+1] = foo();
end
ret = table.concat(ret);
</code>