Run Performance Monitor
Applies to: 
SQL Server - Windows only
Performance Monitor uses remote procedure calls (RPCs) to collect information from Microsoft SQL Server. Any user who has Microsoft Windows permissions to run Performance Monitor can use Performance Monitor to monitor SQL Server.
As with all performance monitoring tools, expect some performance overhead when you use Performance Monitor to monitor SQL Server. The actual overhead in any specific instance depends on the hardware platform, the number of counters, and the selected update interval. However, the integration of Performance Monitor with SQL Server is designed to minimize any reduction in performance.
Note
If you have selected SQL Server performance counters to monitor in the Performance Monitor snap-in, you will see the counters even if SQL Server is not running.
For information about starting Performance Monitor, see Start Performance Monitor (Windows).