>it would be useful to know how netbsd performs as an NFS server 
>compared to solaris.

Depends what solaris is running on and what netbsd is running on.
Many of the `knobs' (tunable or otherwise) on NetBSD (and FreeBSD too)
havent changed since CSRG was running on HP 68030 workstations, or
maybe SS1/decstation3100-vintage risc boxes.  

One day, if I find time, I should write up a list of the tuning I do
when running SpecSFS-like workloads on NetBSD and FreeBSD.  Increasing
ipintrq depth; socket-buffer size; limits on client and server
nfs-helper threads; client-side per-mountpoint readahead; all that
stuff.  (Thanks to Thor Lancelot Simon for pointing some of these
out). I find these make a huge difference when using multiple fast
clients and servers (gig-e, multi-gigahertz CPUs, gigs of memory).

Even so, if you consider multiprocessors, I suspect Solaris has a big
edge for mid- to high-end systems (say, Dell with multiple qlogic
2340s and a rackfull of spindles.)