I have a western digital mybook word NAS. Using the afp protocol file transfers were very slow. I knew there had to be a way to make your AFP NAS more responsive. It seems slow when you try to connect to it from a mac using AFP, but its lightning fast when you connect to it from windows.
The solution (for me at least) was to use a different protocol to connect. I suspect that the afp implementation in the mybook world isnt that great.