slow UID/GID resolving

[vezku at surfeu.fi]

Hi folks,

I'm running FBSD 5.1-RELEASE on SUN E250 ( 2 x Ultrasparc II 450Mhz, 1Gb
RAM). There are about 5000 accounts on that machine and the problem
follows:

File listing is slow. I figured it might have something to do with
resolving UID/GID numbers to names.  It's not too slow on shell, but SSH
file transfer is unbearable. If I try to open a directory with 190
files/subdirs, SSH process eats up all CPU time and it takes 3-4 mins to
get the listing. There is only one UID/GID pair used in this dir.
CPU load average is otherwise under 10%.

I tried both OpenSSH and non-commercial SSH, so it can't be the SSH itself.
And since file listing is slow on terminal too, could there be some other
problem?

Disk load was my next suspection since it has one NFS share, but below is
iostat output. The disk in question is da1 (SCSI U160).

tty             da0              da1              da2             cpu
 tin tout  KB/t tps  MB/s   KB/t tps  MB/s   KB/t tps  MB/s  us ni sy in id
   0   19 13.96   0  0.01  10.86   0  0.00   0.24   0  0.00   0  0  1  0 99

Is the hardware too slow or am I missing something here? Any hints?

-Vesa, SysAdmin