Nah it's not really a legit dock. It's more of an application that appears under your dock that looks like the Leopard dock. It has no functionality and in order to change the size you need to use Terminal. It's more for looks and screenshots than anything.
Ah I downloaded the latest version and it has indeed changed. It's laggy so I don't think it's your computer that affects it, rather it's just the app. Good to see the progress that's come a long though.