Apple's Activity Monitor app is a process monitor app which allows you to monitor, and optionally kill apps in a single window.

The primary two methods for getting rid of an app that just won't go away come down to Force Quit and Activity Monitor.

In Activity Monitor, I look primarily to the CPU, Memory, and Energy tabs to figure out when macOS or a single app is slow, or I’m having peculiar problems with responsiveness.

How to Check Your CPU Usage on Mac with Activity Monitor macOS comes with a built-in utility called Activity Monitor that helps you identify and troubleshoot problematic apps and processes on your ...