Terrible hme throughput

[Frank Jahnke]

I am seeing terrible network throughput on my Ultra 1E+ (a "fast" 1E
clone).  It uses the hme interface; throughputs using scp on a large
file are about 1.3MB/s.  Transferring the same file using scp between
two different, faster computers gives me a throughput of about 8-9MB/s.
This is a 100MB/s network, so that seems OK.

ifconfig shows that hme is set properly (as far as I can tell):

hme0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        options=b<RXCSUM,TXCSUM,VLAN_MTU>
        inet6 fe80::240:dcff:fe3b:21d8%hme0 prefixlen 64 scopeid 0x1
        inet 192.168.0.103 netmask 0xffffff00 broadcast 192.168.0.255
        ether 00:40:dc:3b:21:d8
        media: Ethernet autoselect (100baseTX <full-duplex>)
        status: active

and the MTUs are the same for all machines (and all are FreeBSD 6.1).

Yes, I know that scp has overhead, but I find it hard to believe that
the box could not keep up with it (it is a blazing 300MHz, after all),
particularly for the throughput reduction I see.

Any suggestions on how I can increase the network performance of my 1E+?

Frank