Why is my ModuleScript function timing out?

Repost cause the previous question got no anwers.

function Window.render(Buffer)
    if Buffer == nil then
        Window.getWidth()
        Window.getHeight()
        for i=1,Window.Width + Window.Height do
            local Pixel = Instance.new("Frame")
            Pixel.Size = UDim2.new(0, 1, 0, 1)
            Pixel.BorderSizePixel = 0
            Pixel.Position = UDim2.new(0, i-(i*math.floor(i/Window.Width)), 0, math.floor(i/Window.Width))
            Pixel.BackgroundColor3 = Color3.new(0, 0, 0)
            Pixel.Parent = Window.getInstance()
        end
    else
        for i=1,#Buffer do
            local Pixel = Instance.new("Frame")
            Pixel.Size = UDim2.new(0, 1, 0, 1)
            Pixel.BorderSizePixel = 0
            Pixel.Position = UDim2.new(0, Buffer[i]["Index"].X, 0, Buffer[i]["Index"].Y)
            Pixel.BackgroundColor3 = Buffer[i]["Color"]
            Pixel.Parent = Window.getInstance()
        end
    end 
end

function Window.isCloseRequested()

end

function Window.getWidth()
    Window.Width = game.Players.LocalPlayer.PlayerGui.Render.Frame.AbsoluteSize.X
end

function Window.getHeight()
    Window.Height = game.Players.LocalPlayer.PlayerGui.Render.Frame.AbsoluteSize.Y
end

function Window.getInstance()
    Window.Instance = game.Players.LocalPlayer.PlayerGui.Render.Frame
end

Excerpt of the whole script

The script times out on line 4, not line 3 though despite the fact they are basically the same thing. This is being called from a LocalScript.

Also I'm 90% sure I'm returning stuff wrong since ive never really used ModuleScripts before. If it is wrong please let me know.