I have an application which is having performance problems which have been tracked down to 40% more calls with org.hibernate.event.def.DefaultFlushEntityEventListener.onFlushEntity() on Websphere 8.5.5.1 as compared to the same version of code being deployed on Websphere 6.1.0.41

Details of the hibernate specifics in the software stack are as below:

Websphere 6.1.0.41 with Java 1.5

hibernate-annotations-3.4.0.GA.jar
hibernate-commons-annotations-3.1.0.GA.jar
hibernate-core-3.3.2.GA.jar
hibernate-ehcache-3.3.2.GA.jar
hibernate-entitymanager-3.4.0.GA.jar
hibernate-validator-4.0.2.GA.jar
ejb3-persistence-1.0.2.GA.jar
validation-api-1.0.0.GA.jar


Websphere 8.5.5.1 with JAVA 1.7

hibernate-annotations-3.4.0.GA.jar
hibernate-commons-annotations-3.1.0.GA.jar
hibernate-core-3.3.2.GA.jar
hibernate-ehcache-3.3.2.GA.jar
hibernate-entitymanager-3.4.0.GA.jar
hibernate-validator-4.0.2.GA.jar
hibernate-jpa-2.0-api-1.0.0.Final.jar


The metrics on org.hibernate.event.def.DefaultFlushEntityEventListener.onFlushEntity() are as follows:

Websphere 8.5.5.1

Total Time ( ms) 976,937
Average Time (ms) 16.495
Total Count 59,226


Websphere 6.1.0.41

Total Time ( ms) 760,546
Average Time (ms) 22.666
Total Count 33,554


Does anyone know why there would be more calls to org.hibernate.event.def.DefaultFlushEntityEventListener.onFlushEntity() ?

sorry I have no idea aout Websphere, to find out you should use a profiler.

But if you're really interested in performance you should consider updating Hibernate.
Latest releases are extremely more efficient than those versions you're using.