NFS performance problem

Hello,
we just setting up nfa for unix: i changing ownership and filemode for
whole
exported filesystem (1TB NSS aprox. 4M files)
It is done by shell script from unix side (chmod -R $1 and chgrp -R
$2).
Operation running for 2nd day (!) and now doing letter "k". Server isNW6SP3NSS3b, 2x2.5GHz, 2GB RAM, GBit ethernet and reporting cpu0: 95%utilization in nfsserv xx threads, cpu1: 2%). NSS cachebalance is 80%,

read/write performace is good (about 20MB/s by ftp from my linux
workstation).
Any ideas?
Olda