slow request

Hi !
I am using postgreSQL v8.1.5 with latest odbc driver v8.02.0500.
I have very slow request between my server and my client. They are
both on the same switch 100Mb/s. I have no particular network
problems.
I use the pgadmin tool to do my request.

My database is compose of one table. This table has some simple fields
(varchar & int, less than 500 bytes) and its primary key is a
varchar(32) (CLSID). This table has 140000 records.
I know the primary key as a clsid is not the best choice, but it is
mine :)

The request "select * from mytable" on the server takes
approximatively 30 seconds.
The same request on the client takes approximatively 400 seconds !
What I do not understand is that my network traffic during this
request on the client side is very low. It is less than 100KB/s !

Why is it so slow ? I suppose that my 140000 records are retrieve one
by one... is it true ? if yes, why ?

I try to do the same thing with another table with a primary key as
'int4'. The result is the same : 540 secs to retrieve 150000 records
at 45 KB/s (average speed) (132 octets/record * 150000 = 19MB / 45 KB/
s = 430 seconds)

How can I improve these performances ?
thanks
Mike