Why is this script causing too much lag?

I've made this script, it is scaling a huge box at size about 500x500x500 out of 6 Parts, which kill you on touch. Even though the script works properly, it causes a huge amount of lag. When I checked the Script Performance, it was taking up about 80. Here it is:

Shrinker = script.Parent
StepSize = 0.5 --In Studs
Lenght = 30 --In seconds
ColorTransmissionTime = 5
FinalTransparency = 0.2
Size = Shrinker.Part.Size.X

for i, v in pairs(Shrinker:GetChildren()) do
    if v:IsA("Part") then
        spawn(function()--Spawn function

            v.Touched:connect(function(Hit)
                if Hit:IsA("Part") then
                if Hit.Parent:FindFirstChild("Humanoid") then

                    Hit.Parent.Humanoid.Health = 0--Kill

                    local Explosion = Instance.new("Explosion")--Effect
                    Explosion.Position = Hit.Position
                    Explosion.DestroyJointRadiusPercent = 0
                    Explosion.Parent = game.Workspace
                end
                end
            end)

            v.Transparency = 1

            for i = 1,100-FinalTransparency*100 do
                v.Transparency = v.Transparency - 0.01
                wait(ColorTransmissionTime/(100-FinalTransparency*100))
            end

            for i = 1, Size/StepSize/2 do--Change Size and Position
                local targetCFrame = v.CFrame + (v.CFrame.lookVector * StepSize)
                v.Size = (v.Size - Vector3.new(StepSize*2,StepSize*2,StepSize*2))
                v.CFrame = targetCFrame
                wait (Lenght/(Size/StepSize/2))
            end
        end)
    end
end

Thanks for trying to help! ;)