VoxelArea locality speed test

VoxelArea = {
    MinEdge = {x=1, y=1, z=1},
    MaxEdge = {x=0, y=0, z=0},
    ystride = 0,
    zstride = 0,
}

function VoxelArea:new()
    o = o or {}
    setmetatable(o, self)
    self.__index = self

    local e = {x=10, y=20, z=30}
    o.ystride = e.x
    o.zstride = e.x * e.y

    return o
end

function VoxelArea:getExtent()
    return {
        x = self.MaxEdge.x - self.MinEdge.x + 1,
        y = self.MaxEdge.y - self.MinEdge.y + 1,
        z = self.MaxEdge.z - self.MinEdge.z + 1,
    }
end

function VoxelArea:getExtentF()
    local MaxEdge, MinEdge = self.MaxEdge, self.MinEdge
    return {
        x = MaxEdge.x - MinEdge.x + 1,
        y = MaxEdge.y - MinEdge.y + 1,
        z = MaxEdge.z - MinEdge.z + 1,
    }
end

local iter = 1000000
local prefix = "C  LUA"
if type(jit) == 'table' then -- If it's LuaJIT
    iter = 1000000000
    prefix = "LuaJIT"
end

local x = os.clock()
local v = VoxelArea:new()
local d
for i=1,iter do
    d = v:getExtent()
end
print(string.format(prefix .. " Time  self: %.2f", os.clock() - x))
x = os.clock()
for i=1,iter do
    d = v:getExtentF()
end
print(string.format(prefix .. " Time local : %.2f", os.clock() - x))