Mac Performance

How to Use Activity Monitor (Mac Task Manager)

If you are searching for a definitive guide on how to use Activity Monitor, the Mac Task Manager, look no further.  


Before we start


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After reading this guide, you will be able to:

  1. Open a task manager on your Mac
  2. Check CPU usage and list processes by %CPU
  3. See how much memory your Mac is using
  4. Review your Mac’s energy usage with Activity Monitor
  5. Work with Activity Monitor’s Disk Pane
  6. Use the Network tab in Mac Activity Monitor
  7. View cache information
  8. Generate a system diagnostics report
  9. View detailed information about an app or a process
  10. Force quit apps from a Mac’s system monitor  


But first, let’s take a look at what Activity Monitor is.

What is Activity Monitor

Activity Monitor is a built-in macOS tool that can help you to improve your Mac’s performance, fix slow apps, and keep the most common hardware and software issues at bay. In other words, Activity Monitor is just like Windows’ Task Manager — an app that helps you to monitor the running processes on your Mac.  


Once you open this Mac performance monitoring tool, you’ll be able to see five panes that give you a complete overview of your Mac’s performance:

  • CPU pane: Shows all the apps and processes that use your Mac’s processor
  • Memory pane: Shows all the apps that use your Mac’s memory
  • Energy pane: Shows all the apps and processes that can drain your battery’s energy
  • Disk pane: Shows how much data each process and app reads or writes to your disk
  • Network pane: Shows how much data is being sent or received through your entire network and displaying network-based processes
activity monitor window open in the CPU pane

Pro tip: You can add or remove some of these panes using the View menu.  

How to open a task manager on a Mac

There are two ways to do it.  


To open Activity Monitor on a Mac with Finder:

  1. Open Finder
  2. Select Applications
  3. Choose Utilities
  4. Double-click the Activity Monitor icon (the pulse icon)
How to open a task manager on a Mac   There are two ways to do it.    To open Activity Monitor on a Mac with Finder: Open Finder Select Applications Choose Utilities Double-click the Activity Monitor icon (the pulse icon)

The second and the fastest way to open the MacBook task manager is to use Spotlight:

  1. Click the magnifier icon in the top right corner or simply press Command (⌘) + Space
  2. Type in Activity Monitor
  3. Hit the Enter key
search for activity monitor in spotlight

How to check CPU usage on a Mac

In Activity Monitor, you can see how much certain apps and processes are burdening your Mac’s processor or CPU.  


To open CPU usage on a Mac, go to View All Processes %CPU, and this will sort the processes by the percentage of the processor capability used.

activity monitor window with processes sorted by CPU usage

Some apps or processes can severely drain your CPU resources. However, this is not always an indication of a problem. For instance, there are a few perfectly normal processes that can cause CPU spikes:

  • mds and mdworker: Those are Spotlight indexing-related processes that can slow down your Mac and cause frequent CPU spikes. However, it’s completely fine and it will end automatically once the indexing is finished
  • Kernel_task: This process helps to manage your Mac’s temperature by limiting your CPU resources to prevent overheating. For more information, check this article on how to prevent your Mac from overheating
  • Rendering: Some apps such as video editing and music production apps require a lot of your CPU resources. Therefore, it’s okay to find CPU spikes if you are rendering or uploading big files


You can check the bottom of the window for more in-depth details on your Mac’s CPU usage and loads:

  • System: The percentage of CPU currently being used by your Mac’s system processes
  • User: The percentage of CPU that is currently being used by the apps you opened and their processes
  • Idle: The percentage of your available free CPU capacity (CPU capacity that is not being currently used)
  • CPU load: The percentage of CPU that is currently used by all your system and user processes (Simply merging the System usage and the User usage)
  • Threads: This shows the total number of threads that are currently used by all the processes combined
  • Processes: The shows the total number of processes that are currently running
the statistics pane at the bottom of the activity monitor %CPU tab

Pro tip: Get a Mac CPU usage statistics at your fingertips.  

Create a graph widget by going to Window → CPU Usage (or use Command (⌘) + 2).


Also, you can display the processor load right in your Dock. Just go to View → Dock icon → Show CPU Usage.

dock icon in the view settings in activity monitor

Moreover, there’s a quick way to check the recent processor activity. Use either:  

  • Window → CPU Activity 
  • View → Dock Icon → Show CPU History

Seeing how much memory your Mac is using

When you’re using a lot of memory, your Mac tends to slow down. The Activity Monitor’s Memory pane can help you deal with that. Here, you can find the following information:

statistics in the bottom pane of the memory tab in activity monitor
  • Memory pressure: It shows how much memory or RAM your Mac is using at the moment and the current state of memory resources is indicated by the color next to the graph:
    • Green: Your Mac is using its RAM efficiently
    • Yellow: Memory resources are still available to use but they are tasked by memory-draining processes such as compression
    • Red: There’s a lack of memory. If your Mac is running out of memory, quitting some apps should help. If you’re constantly running out of memory, you can install more RAM.
  • Physical Memory: It shows the amount of RAM installed on your Mac
  • Memory Used: It shows the amount of memory currently being used by all apps and processes. For example, If your Mac has 16GB of RAM installed, but at the moment your Mac is only using 9GB, you’ll see it in the Physical Memory and Memory Used sections respectively.
  • Memory Used is also divided into three different types:
    • App Memory: The overall amount of memory that is currently being used by apps
    • Wired Memory: Memory that can’t be compressed
    • Compressed Memory: The total amount of memory that is compressed to make more memory available for other processes
  • Cached Files: This is the memory that has recently been used by apps and now it’s available to be used by another app. For instance, if you were using Mail and you closed it, the RAM that Mail was using would now become a part of the Cached Memory. If you open Mail again before the Cached file’s memory being overwritten, then Mail will open more quickly because your Mac won’t need to fetch data all over again
  • Swap Used: It indicates how much space on your startup drive is reserved for macOS memory management processes

If you do notice your RAM usage spiking and it slows down your computer, trying running a memory cleaner for Mac. You might still need to delete whatever's hogging your RAM, but a cleaner can at least give you a quick speed bump.

Reviewing energy usage with Activity Monitor

Some apps can really drain your battery and the Mac process manager can give you information on the overall energy used by each app and process.


Luckily for Mac users, Activity Monitor’s Energy pane gives you the power to stop battery-killing apps and processes in order to extend the battery life of your MacBook.  

energy tab in activity monitor

For more in-depth details on your Mac’s energy usage, you can check the following columns:

  • Energy Impact: It helps you to find how much energy a certain app consumes. For more information, click the small triangle ► next to the app’s name to expand a list of child processes

Pro tip: If you want to find how much energy a specific app consumes, use the search bar in the upper right corner of the Activity Monitor window

  • Average Energy Impact: This column displays how resource-intensive your apps and processes have been for the past 8 hours or since the Mac last started up. Needless to say, the lower the numbers the better
  • App Nap: This shows if the app uses the energy-saving App Nap technology. For example, if your Finder window is hidden behind other windows, then Finder is napping and not hogging your battery
  • Preventing Sleep: It shows if the app or process is preventing your Mac from going into sleep mode

Further, you can find more useful information at the bottom of the pane, including:

  • Energy Impact: It’s a graph of the total energy used by all apps and processes. This graph moves from right to left
  • Graphics Card: This shows the type of graphic card being currently used. Most MacBooks have two graphics cards; one is higher performance (higher energy consumption) and the other one is an integrated graphics card (lower performance and lower energy consumption). Make sure to enable graphics switching in order to improve your battery life and prevent your MacBook from overheating
  • Remaining Charge: This shows the percentage of charge remaining in the battery
  • Time Remaining: This shows how long your MacBook can survive on a battery alone
  • Time Until Full: This shows the expected amount of time your Mac needs to be fully charged
  • Time on AC: This shows the elapsed time since you plugged in your Mac
  • Time on Battery: This shows the elapsed time since you unplugged your Mac
  • Battery: This shows the battery charge activity over the past 12 hours

As a rule of thumb, the higher your energy consumption is, the shorter your Mac can survive on a battery alone. Hence, if your Mac’s battery life feels shorter than usual, closing the apps that use a lot of energy can improve your battery life.


Finally, you can pin the graph of energy usage to your Dock by going to View → Dock Icon → Show Disk Activity.

Working with Activity Monitor’s Disk pane

In the Disk pane, you can check the amount of data each process reads and writes to your disk. This pane also shows the Reads in and Writes out processes (I/O), which is the total number of times your MacBook accesses the disk to read or write data.

disk tab in activity monitor

At the bottom of the Disk pane, you can find the Disk Activity graph, which is the total disk statistics across all the system activities. It includes a menu to switch between I/O or Data as a unit measurement.  


The graph has parameters in two colors:

  • Blue: It shows the number of reads per second or the total amount of data your Mac reads per second
  • Red: It shows the number of writes out per second or the total amount of data your Mac writes out per second

 You can pin the graph of disk activity to your Dock by going to View → Dock Icon → Show Disk Activity.

Using the Network pane in Activity Monitor

This pane displays all network-related processes, including how much data is being sent (uploaded) or received (downloaded) over your network.  

network tab in activity monitor

Just as with other panes, you can check the total number of data sent/received in the Network Activity graph at the bottom of the pane.


Network Activity graph also includes a menu to switch between showing packets or data as a unit of measurement.


The graph has parameters in two colors:

  • Blue: It shows the number of packets downloaded per second or the total amount of data your Mac downloads per second
  • Red: It shows the number of packets uploaded per second or the total amount of data your Mac uploads per second


You can also display the Network Activity graph in your Dock by going to View → Dock Icon → Network Usage.

Viewing cache information

ِYou might not have this pane in Activity Monitor. It is only available starting from macOS High Sierra and if content caching is enabled. The Cache pane shows how much cache content your local network devices have sent, received, or dropped over time.


You can also use the Maximum Cache Pressure information to figure out whether to modify content caching settings or to provide more disk space.  


Don’t worry if your cached files are consuming a lot of memory. The only indicator here is Cache Pressure: the lower the percentage is the better. In other words, as long as cache pressure is green you are ok. You can see the past cache activity over the last hour, 24 hours, 7 days, or 30 days.

Generating a system diagnostics report

Another useful task manager’s built-in feature is system reports. This feature helps you to monitor your Mac by generating a system report that you can send to Apple support to help you troubleshoot your Mac.


To generate a system diagnostics report, go to View ➝ Run System Diagnostics.

find the system diagnostics option in the view menu in activity monitor

In a few minutes you’ll get a zip file generated and displayed in Finder.  

How to force quit applications using Activity Monitor

It’s a good idea to check the way the app is using your system resources in case it’s frozen.  


Open Activity Monitor (CPU pane) and find the non-responding app on the list. If it uses too much CPU or memory, try to force quit it. Just highlight the app and click the X button in the upper left corner of the Activity Monitor window.

force quit energy consuming photo booth app in activity monitor

Alternatively, you may use four other methods to force quit a frozen Mac app.

How to view additional information about an app or a process

You can check for more details on a specific process by double-clicking on it in the Activity Monitor. You’ll see the general process and memory statistics as well as some advanced parameters (e.g., open files and ports that the app is using).


1. Why does the Mac task manager use so much CPU?

There can be numerous reasons causing your Activity Monitor to use so much CPU. However, when there is a big load on the CPU and you decide to open Activity Monitor, then it will take a huge amount of the CPU resources just to open itself.


Be aware that Activity Monitor won’t fully load until the GUI loads on the screen first. As a result, you will see this huge ramp-up in CPU load even after the GUI appears on the screen, which causes the 100% CPU usage you see.

2. How to stop Activity Monitor on a Mac?

To stop Activity Monitor:

  1. Select the Activity Monitor app in the Activity Monitor window
  2. Click on the X button in the top left corner
  3. Choose one of the following options:
  • Quit
  • Force Quit (if quit doesn’t work)

3. How to use Activity Monitor to speed up a Mac?

Some apps can drain all your Mac’s resources. Just as discussed in this guide, if you notice an app or process that uses a lot of your memory, disk, CPU, etc., force quit this app and you will notice a great improvement in your Mac’s performance.

4. How to identify malware using Activity Monitor?

You can check Activity Monitor for any uncommon apps or processes that drain your system resources and stop them. However, you may accidentally stop useful processes this way and scanning for malware manually can get truly demanding.


Therefore, you should consider using a third-party security solution such as MacKeeper to help you quickly and efficiently scan for malware through all your files.

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