output.md

$ src/luajit test1.lua                                            
test3/lua 0.000812
test2/lua 0.047739
$ src/luajit test2.lua
test2/lua 0.050938
test3/lua 0.000856

test1.lua

require "vector3"
collectgarbage()
test3()
collectgarbage()
test2()

test2.lua

require "vector3"
collectgarbage()
test2()
collectgarbage()
test3()

vector3.lua

local Vector3 = { __typename = 'Vector3' }
do
        local setmetatable = setmetatable
        local I = { __typename='Vector3' }

        Vector3.__call = function(t, x, y, z)
                return setmetatable({x or 0, y or 0, z or 0}, I)
        end
        setmetatable(Vector3, Vector3)
end

function test2()
        local start = os.clock()
        for i = 1,200000 do
                local up = Vector3(0,1,0)
                tostring(up)
        end
        print("test2/lua " .. (os.clock() - start));
end

function test3()
        local start = os.clock()
        for i = 1, 2000000 do
                Vector3(i, i, i)
        end
        print("test3/lua " .. (os.clock() - start));
end