for local communication only - UNIX or INET?

I'm mostly curious - wath are the pros and cons of using a local UNIX socket vs. an INET socket? E.g. having a daemon listen on /var/lib/xxx/yyy.soc instead of localhost:nnnnn ? (it is assumed that everyone involved will have the choice of using either one). Any likely performance impacts (positive or negative)? /Per Jessen, Zürich