Hibernate Session Factory is expensive-to-create

Question

I read everywhere that Hibernate SessionFactory is expensive-to-create operation. But there is no clarity on what is the expensive part ? Can anyone please explain.

Answer 1

According to this: "The SessionFactory maintains services that Hibernate uses across all Session(s) such as second level caches, connection pools, transaction system integrations, etc."

I guess that creating all this services must be an expensive task.