Hiya!

>> Thanks for the tips, I'll keep looking what else I can find.
> Hm, first test would be to use a cross cable to talk directly to another
> 10 Mbit machine.... if you don't depend on some NFS server, of course.
> also check the statistics you get by netstat -s, for excessive broken
> packets, retransmits, etc.

As I am currently only using AmigaOS I can unfortunately not provide
solution ideas for NetBSD, but I hop it will help nevertheless.

I had the same problems with veeerrry lame transfers if connected from my
linux box to my Amiga by ftp and not being able to write to my nfs device
on my linux box from my Amiga (reads are possible, I have been streaming
mp3s for a long time, hehe). My Amigas are connected via TP to a hub, which
in turn is connected to the linux box via coax.

Then I tried several things and found the problem in the packet size:

The default (at least for the amiga nfs client from AmiTCP) is a write size
of 8192 bytes (according to the docs). I changed this via the MAX_WRITESIZE
option (at the according line in AmiTCP:db/ch_nfstab) to 4096 and it just
works, the LEDs at my hub are happily blinking all the time now and writes
to the nfs device are now possible, hehe. The one thing to wonder: Amster
has been able to write to nfs all the time, it uses smaller block sizes one
assumes...

I then added -b8 to the ftp line in inetd.conf for 8x512 bytes as max packet
size and my transfer speed if downloading from my Amiga to Linux via ftp
jumped from mere 60-70KBps to 260-270 KBps.

So it could be that for you also, hope it helps.

Ciao, Rockus
-- 
"I *love* the smell of crashed code in the morning!"
  - a bug in "Cyberworld"