Alex CD ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=557058%... ) *updated* an issue Hibernate ORM ( https://hibernate.atlassian.net/browse/HHH?atlOrigin=eyJpIjoiNWIxODY1NGU5... ) / Improvement ( https://hibernate.atlassian.net/browse/HHH-14093?atlOrigin=eyJpIjoiNWIxOD... ) HHH-14093 ( https://hibernate.atlassian.net/browse/HHH-14093?atlOrigin=eyJpIjoiNWIxOD... ) Optimize inserted key contains ( https://hibernate.atlassian.net/browse/HHH-14093?atlOrigin=eyJpIjoiNWIxOD... ) Change By: Alex CD ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=557058%... ) In a transaction where many entities are inserted, the performance when getting an entity is degrading at: StatefulPersistenceCotnext.java: {code:java} @Override public boolean wasInsertedDuringTransaction(EntityPersister persister, Serializable id) { // again, we only really care if the entity is cached if ( persister.canWriteToCache() ) { if ( insertedKeysMap != null ) { final List<Serializable> insertedEntityIds = insertedKeysMap.get( persister.getRootEntityName() ); if ( insertedEntityIds != null ) { return insertedEntityIds.contains( id ); } } } return false; } {code} *insertedEntityIds* list may contain more than 10 100.000 entries that affect performance of *ArrayList.contains* which has *O( n )* complexity. Please replace *ArrayList* with *HashSet* for better _contains_ performance. ( https://hibernate.atlassian.net/browse/HHH-14093#add-comment?atlOrigin=ey... ) Add Comment ( https://hibernate.atlassian.net/browse/HHH-14093#add-comment?atlOrigin=ey... ) Get Jira notifications on your phone! Download the Jira Cloud app for Android ( https://play.google.com/store/apps/details?id=com.atlassian.android.jira.... ) or iOS ( https://itunes.apple.com/app/apple-store/id1006972087?pt=696495&ct=Em... ) This message was sent by Atlassian Jira (v1001.0.0-SNAPSHOT#100131- sha1:a811519 )