MDS 2012 --> MDS 2016, permissions: expand tree of entities - very very long

Important!!!

I did Upgrade the database with MDS 2012 --> MDS 2016 (SQL Server 2016 EE SP1). Upgrade was successfully.
When trying to edit an existing user, to set permissions, expand a tree of entities (press +) --> expand very very long .
The web app breaks down on timeout. Statistics at the database level has been updated. Server is new, one active session.

from Moscow with money