Slow query through ODBC

Hi all !

I have a query that runs very fast when executed through pgAdmin
(~2 seconds), but very slowly through the ODBC driver (~30
seconds). Both queries are executed from the same workstation on
the same server.

My workstation is a WinXP Pro, and I use the latest psqlODBC
driver available as an MSI package (version 8.01.0102).
The server is a PostGreSQL 8.1.2, running on a Win2000 server.

The query is very simple, it returns about 1500 lines, made of
only one text field, but this field can be very large (it is the
WKT representation of a spatial object from PostGIS).

I am connecting to the server in a VBA project with a simple
connectionstring with only default options (I have not found a
document explaining how to fine tune the odbc driver).
My connectionstring is :
"DRIVER={PostgreSQL
Unicode};SERVER=myserver;PORT=5432;DATABASE=mydatabase;UID=myuser;PWD=mypass"

I assume that the problem is with the very large field size that
is returned, but what should I change in my connectionstring to
make this query run faster ?

Thanks for your help !

--
Arnaud