By default db4o uses weak references to keep track of loaded objects. These weak references need to be clean up from time to time. You can change this collection-interval.
IEmbeddedConfiguration configuration = Db4oEmbedded.NewConfiguration(); configuration.Common.WeakReferenceCollectionInterval = (10*1000);
Dim configuration As IEmbeddedConfiguration = Db4oEmbedded.NewConfiguration() configuration.Common.WeakReferenceCollectionInterval = (10 * 1000)