You're analysis looks correct to me. The synchronization is something to take up with the Hibernate folks on the hibernate.org forums, as its part of their general 2nd level cache management; not something controllable by JBoss Cache. Inside isUpToDate(), before calling into JBC, the Hibernate/JBC integration layer suspends any ongoing tx and then resumes it on exit. If your query involves lots of entities, that will happen multiple times. That could be expensive. If you find that query caching slows down your app, don't do it. :) Also, you mentioned a deadlock. Is there a deadlock? Your discussion is of thread contention, which is not the same thing as a deadlock. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4084008#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...