Performance over a LAN

Hello,

Using a test client application that performs 100000 insert operations on a
table, with the client application running on the same machine as the
Postgres server, I get the following results for the time taken to run the
test:

Unix domain socket connection: 26 seconds
Inet domain socket ('localhost'): 35 seconds

The table has two columns, a timestamp and a character(16), no indexes.

But with the server running on one machine and the client running on
another, the two machines being connected by a 100 Mb ethernet, with nothing
else on the network, this test takes 17 minutes to run. I have tried
changing the frequency of COMMIT operations, but with only a small effect.

The machines used are P4s running FreeBSD 5.2.1. The Postgres version is
7.4.3. Can anyone tell me why there's such a big difference?

Thanks,
William