Store Video Clips on local machine or NAS?

I am planning on setting up a simple home file server for my father to store his pictures, music, and video clips that he records with his video camera. His hobby is turning these home videos into movies using Sony Vegas Studio (version 8 or above i think).

If he is building a project should he store the raw clips locally until he renders his final movie, and then move the clips to the server? Or should he always keep the clips on the server?

My thought is that keeping the clips on his local machine will make editing and rendering much faster and smoother. Is this true?

Thanks,
Armethius