Copy to Csv file extremely slow

Hi, I´m using the copy command to generate a csv file, but the generation its extremely slow in a production server. In our test's server this copy takes 20 minutes but in a production server this takes 2 days.

The database that i used to the tests is a copy of the production database.
The machines are totaly differents. Test Server is a simple Intel core 2 duo 2.8 ghz with 8 GB Ram and Production Server has 2 xeon 2.8 ghz with 24 GB RAM.

Before the tests we ran vacuum and closed all another connections.
The query takes 19 minutes and file generation less than 1 minute to create a file with 473 MB in the tests server. In Production server the query runs in the same 19 minutes, but file generation 2 days.

I'm running postgresql 9.0 on CentOS 6.3 on both machines.

Any idea about this big difference.

Thanks , and sorry by my english.