What's the most efficient way to implement classes in Lua? - lua

Question

By efficient, I mean performance wise. If you have to access class members rapidly, like when drawing UI, what is the best way to index them?
My understanding is that table-based classes use less memory and are faster at creating instances, while closure-based classes have faster function calls and let you have private fields which are quickly indexed because they are stored as upvalues. What's the best implementation for a situation like the example class below?
-- Example of Table-based Class
local class = {}
class.x = 0
class.y = 0
class.w = 0
class.h = 0
-- Draw would be called for potentially dozens of instances many times per second
function class:Draw()
draw_rect(self.x, self.y, self.w, self.h)
end
-- Example of Closure-based class
local function class(_x, _y, _w, _h)
-- the new instance
local self = {
-- public fields
visible = false
}
-- private fields are locals
local x, y, w, h = _x, _y, _w, _h
function self.SetPos(_x, _y)
x = _x
y = _y
end
function self.GetPos()
return x, y
end
function self.GetVisible()
return self.visible
end
-- return the instance
return self
end
local obj = class(10, 20, 40, 80)
print(obj.GetPos()) --> 10, 20
obj.SetPos(50, 100)
print(obj.GetPos()) --> 50, 100
obj.x = 21
obj.y = 42
print(obj.GetPos()) --> 50, 100 (unchanged, private)
obj.visible = true
print(obj.GetVisible()) -- true (public)