> And because indexing by string is more harder task, including hash calculations if it's using hashtables as implementation FWIW, Lua uses string interning (h

> And because indexing by string is more harder task, including hash calculations if it's using hashtables as implementation FWIW, Lua uses string interning (https://en.wikipedia.org/wiki/String_interning https://en.wikipedia.org/wiki/String_interning). The hash calculation for looking up _G["print"] occurred at compile time. _G["print"] should be as quick as indexing an array because the hash calculation is memoized and comparing string equality is equivalent to testing pointer equality. (Indeed, in a simple test both _G["print"] and _G[42] take about 1/10th of a second to iterate 4 million times on my circa 2012 Core i7.) That said, using lexically bound locals (aka upvalues in Lua parlance) is indeed faster as loading the variable becomes a simple pointer dereference through the [anonymous] function object. A simple test suggests about 25% faster.