I'm running Drupal 7 with PostgreSQL as a Q&A (with a lot of nodes inserts/updates and several contrib modules). Do you recommand any particular pgsql vacuum policy on particular tables ?
In theory you can run your database optimization commands any time you want, but I think at least bi-weekly helps. However, if by running database optimization commands you intend to improve the performance of your site by more than 5%-10%, I'm afraid no vacuum optimization policy will do. You will need to utilize traditional performance troubleshooting procedures such as checking all your server's error logs, access logs, database slow query logs, as well as taking in consideration your peak and average load versus your current architecture.