Performance Monitor is described as 'Small program that shows you the CPU, Memory, Disk and Network utilization under Windows NT platforms (2000, XP, Vista, Win 7, etc...)' and is a Network Monitor in the network & admin category. There are more than 10 alternatives to Performance Monitor for a variety of platforms, including Windows, Linux, Mac, BSD and Self-Hosted apps. The best Performance Monitor alternative is Resources, which is both free and Open Source. Other great apps like Performance Monitor are Process Monitor, Task Manager, GNOME System Monitor and StatusPilatus.