The MSRS 2014 Windows Service: Active Session performance counter in Windows Performance Monitor incorrectly displays a very high value for Microsoft SQL Server 2014 or 2016 Reporting Services.
The issue was first fixed in the following cumulative updates of SQL Server:
Each new cumulative update for SQL Server contains all the hotfixes and all the security fixes that were included with the previous cumulative update. We recommend that you download and install the latest cumulative updates for SQL Server:
Learn about the terminology that Microsoft uses to describe software updates.