Are methods unefficient?

So, if I am doing a module script with several functions, example:

local _M = {}

function _M.Print()

end

function _M.DoSomething()

end

function _M.DoAnotherThing()

end

function _M.Whatever()

end

return _M

It’s advised that I store them all in a script I want to use them? And should I not use methods at any cost?