Hi, Sanne and I identified a few hot spots in Hibernate Core 4 especially when used with Hibernate OGM (which does use lighter weight datastores so to speak). The most significant one in term of code fix is HHH-6735 which now caches and guard FieldInterceptorHelper methods per class when a SessionFactory is known. This proves to be a significant performance boost for us. On simple CRUD operations (inserts I believe), we are about 50% faster. I believe this improvement will show up in regular Core users especially ones with big persistence context to flush. Of course such a code change comes late in the 4.0 development cycle but I think it's worth it. Keep an eye on forums and JIRA for people complaining about bytecode enhanced classes not behaving as expected. I've committed the change in master. Emmanuel