If you want to keep an eye on the CPU or GPU usage on your Mac, you can enable several little-known performance windows in Activity monitor. These float above all other app windows, so you can check them out at a glance.
To enable them, press Command + Space or click the magnifying glass icon in the menu bar to open Spotlight search. Type “Activity Monitor,” then press Enter.
Click on “Window” at the top. In this menu, you will see choices for “CPU Usage”, “Processor History” and “GPU History”. Each of these opens a floating window that will give you information in real time.
Let’s see how each of these panels works.
The floating processor usage panel
If you click “Processor Usage” on the “Window” menu (or press Command + 2), a small window appears that includes a 10-segment gauge for each processor core.
Each gauge lights up based on processor activity in that particular core. For example, if five segments are lit, you are using 50% of the processor capacity of that core.
The processor history floating panel
If you click “Processor History” in the “Window” menu (or press Command + 3), a window divided into several boxes appears. Each box corresponds to a core inside the CPU and displays updates slowly, from right to left.
The height of the dots in each column corresponds to the intensity of processor activity in that core. Red squares represent processor activity by system processes, while green represents processor activity by user processes.
The floating GPU history panel
If you select “GPU History” from the “Window” menu (or press Command + 4), you will see a graph showing the history of graphics processor (GPU) usage on your Mac. The more active your GPU is, the more blue dots appear during each update, as the graph flows from right to left.
As to what exactly the blue squares in the graph represent, we’re not sure (even the official Apple documentation is not clear about that). However, the graph provides a rough visual estimate of the work force of the graphics hardware.
Changing the Performance Window Update Interval
By default, each performance panel is updated every five seconds. If you want to change this, click View> Update frequency in the menu bar. In the submenu you can choose between “Very often (1 s)”, “Often (2 s)” or “Normally (5 s)”.
Note that on older systems, updating graphics more frequently may slightly decrease overall system performance. On most modern Macs, however, the effect will be negligible.
Set a performance window to stay visible
If you want to keep one or more CPU or GPU performance panels on screen, you can float them on top of all the other windows. To do this, click Window> Keep Processor Windows at the top of the menu bar.
If you don’t want to see the main “Activity Monitor” window, just click the red “X” to close it. If you want to open it later, just click Window> Activity Monitor in the menu bar or press Command + 1.
The Activity Tracker has more to offer than most people realize. If you delve deeper into its features, you can learn a lot more about how your Mac works. For example, you can even use the Activity Monitor Dock icon as a processor monitor!