Consider the following scenario:
You enable transparent data encryption (TDE) in SQL Server.
You use asymmetric encryption keys to protect the backup of the SQL Server database.
You store the asymmetric encryption keys in the SQL Server Extensible Key Management (EKM) provider.
You restore the backup of the SQL Server database.
In this scenario, it may take a long time to complete the restore, due to unnecessary communications with the EKM provider.
This issue is fixed in following cumulative updates
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
Learn about the terminology Microsoft uses to describe software updates.