hibernate/hibernate-core — pull request #208 by ockernutser (2011-11-03 13:33:19+00:00)
Title: Performance Optimization of in memory merge algorithm.

Merging of large entity graphs was slowed down by a copy to entity map which was created on the fly for every merged entity.
This created quadratic rising execution time vs nr of entities.
It is resolved by keeping a map copy to entity directly in sync with the existing entity to copy map in the EventCache code.