RODC No Accounts Cached model

Hi,

We're considering deployment of RODC to our remote sites due to lack of good physical security. I've been reading this article: http://technet.microsoft.com/en-us/library/cc730883%28v=ws.10%29.aspx and need more info about the default setup for RODC (no password will be cached on the DC). Can anyone help explaining the PROs that this enumerates, particularly this part:

"Most secure, still provides fast authentication and policy processing"

How can it provide fast authentication and policy processing?