Hibernate Performance Tuning

Recently, I am involved in a hibernate performance tuning project. We used to use Oracle Toplink as the Object-Relational mapping tool for our application. Several months ago, we decided to switch to the more popular JPA/Hibernate.

However, after the switch, we experienced wide-spread performance slowdown. To tune the performance of Hibernate, I did a thorough research in related articles. The more I dug in, the more I realized that performance tuning is a systematic effort. There are a lot factors contributing to the performance of Hibernate. I would like to list our experience here as a reference to everyone who use Hibernate.