>However, this still seems very slow: I understand pipes are implemented
>internally using sockets. Is there some explanation as to why this is the
>case? A 133MHz FreeBSD machine appears to be several times faster than the
>equivalent NetBSD system, as does Linux.

John Dyson re-did pipes in freebsd to make them faster.
this work was ported to OpenBSD and appears in src/sys/kern/sys_pipe.c
in the OpenBSD source tree.  I would suspect that it can be 
made to go in NetBSD also (something you might want to play
with if you have the spare time...).

chuck