PostgreSQL Dump rate is too slow

We have a customer who has 1TB database on a production server. They are trying dump based backup of this large database. Following dump command is being used. 

Dump rate is around 12 GB/hr, which will take lot of time for the backup to complete. This is affecting their production server.  

Is there is a way to increase dump data rate ?

pg_dump -U <User> -Fc -b --port=<Port> '<Db-Name>'

PostgreSQL version : 9.2.4

Platform : Linux

Thanks

Girish