Macs are famous for their stability, but occasionally, an application will completely freeze. Whether it is a heavily modded video game or a web browser struggling with a malicious script, the app will stop responding, the “spinning beachball of death” will appear, and clicking the red ‘X’ window button does absolutely nothing. When an application refuses to close normally, you must forcefully terminate it. While the keyboard shortcut (Command + Option + Esc) is the most well-known method, the macOS Activity Monitor is the ultimate diagnostic tool for hunting down and killing rogue processes.
Opening the Activity Monitor
The Activity Monitor is the macOS equivalent to the Windows Task Manager. It is a built-in utility that shows you exactly how much CPU, RAM, and network bandwidth every single running program is using.
- Press Command + Spacebar to open the Spotlight Search bar in the center of your screen.
- Type Activity Monitor and press Enter.
- The Activity Monitor window will open, displaying a constantly updating list of processes.
Identifying and Force Quitting a Frozen App
If an app has frozen completely, the Activity Monitor usually identifies it immediately.
- Look at the main list of apps in the Activity Monitor. If an app is truly frozen, its name will appear in red text, followed by the phrase (Not Responding).
- If it does not say “Not Responding,” but you know a specific app is making your Mac run hot and slow, click the % CPU column header at the top to sort the list. The app using 99% of your processing power will jump to the very top.
- Click once on the name of the problematic app to highlight it in blue.
- In the toolbar at the top of the Activity Monitor window, click the Stop button (it looks like an octagon with an ‘X’ inside it).
- A confirmation dialog box will appear. You have two options:
- Quit: This asks the application nicely to save its data and close itself. (This rarely works on frozen apps).
- Force Quit: This tells the macOS kernel to instantly sever all ties with the application and dump it from memory without saving any data. Click this option.
The app will instantly vanish from your screen and from the Activity Monitor list, immediately freeing up your system resources.
A Warning About Background Processes
The Activity Monitor displays not just visible apps (like Safari or Mail), but also hundreds of invisible background processes (like kernel_task, mds_stores, or windowserver). Never Force Quit a process if you do not know what it does.
Many of these cryptic processes are critical to the macOS operating system. If you force quit windowserver, your entire graphical interface will crash, and your Mac will immediately log you out, forcing you to lose all unsaved work across all your open applications.