Ive updated http://www.zope.org/Members/htrd/cache with a release of the new ZODB cache which uses weak references on ghosts but not non-ghosts. This version also supports ZClasses. I think this version would be worth trying for anyone who has had problems with ZODB using too much memory. I would be grateful for any feedback. Toby Dickenson tdickenson@geminidataloggers.com