Performance and synchronization polishing

Related issues:
 - https://hibernate.atlassian.net/browse/HHH-8679
 - https://hibernate.atlassian.net/browse/HHH-8680
 - https://hibernate.atlassian.net/browse/HHH-8681
 - https://hibernate.atlassian.net/browse/HHH-8682
 - https://hibernate.atlassian.net/browse/HHH-8698