Repeating a function, what's the best way to do it, with minimal lag etc?

I currently only know of two ways, a third I'm unfamiliar with which I'm not sure would work. What's the most efficient way of repeating something over again, for example let's say you have a repeating game that has to call on a function/s that set up the game for people play. Is there another way that I've yet to find, (likely).

One:

while true do
--code
wait(--[[whatever time is set]])
end

Second:

--Currently using this below, over the while true do ... end
function a()
wait(1)
a()
end

Third: I'm not very familiar with these but coroutine's are these a viable way of setting a loop or something that must be called again and again?