copy and postgresql.conf

hi,

i load data from files using copy method.
Files contain between 2 and 7 millions of rows, spread on 5 tables.

For loading all the data, it takes 40mn, and the same processing takes 17mn with Oracle.
I think that this time can be improved by changing postgresql configuration file.
But which parameters i need to manipulate and with which values ?

Here are the specifications of my system :
V250 architecture sun4u
2xCPU UltraSparc IIIi 1.28 GHz.
8 Go RAM.

Regards.

Will

This e-mail is intended only for the above addressee. It may contain
privileged information. If you are not the addressee you must not copy,
distribute, disclose or use any of the information in it. If you have
received it in error please delete it and immediately notify the sender.
Security Notice: all e-mail, sent to or from this address, may be
accessed by someone other than the recipient, for system management and
security reasons. This access is controlled under Regulation of
Investigatory Powers Act 2000, Lawful Business Practises.