If you have performance problems with a backup of a large PostgreSQL database, then you may consider incremental or differential backups.
An incremental backup is a backup of all files that have changed since the last backup, either incremental or full. In order to restore a given incremental backup, you must restore the full backup and then all the incremental backups in between.
A differential backup is a backup of all individual changes since the last full backup. In order to restore a differential backup you need only that backup and the full backup it refers to.