Assume that you have an AlwaysOn Availability Group that contains many databases in SQL Server 2016. For example, you may have more than 100 databases. When you execute a query that requests data from the sys.dm_hadr_availability_replica_states function and the query contains many join operations, the query may take a longer time to complete when you compare it to an earlier version of SQL Server. Additionally, it may also cause high CPU usage.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.