Assume that you use Transparent Data Encryption (TDE) together with Extensible Key Management (EKM) in Microsoft SQL Server 2017, 2016 and 2014. You may notice that database backup and restore operations are slow if the encryption key for a TDE-enabled database is stored in the EKM provider.
This problem is fixed in the following updates for SQL Server:
Cumulative Update 1 for SQL Server 2016 Service Pack 2
Cumulative Update 9 for SQL Server 2016 Service Pack 1
About SQL Server builds
Each new build for SQL Server contains all the hotfixes and security fixes that were in the previous build. We recommend that you install the latest update for your version of SQL Server:
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
Learn about the terminologythat Microsoft uses to describe software updates.