Here are some questions and problems that people often encounter when using App Tamer. Before consulting this list or contacting us, please make sure you are using the latest release of App Tamer, version 2.5.2.

If you have a problem that is not addressed here or feel a question should be here but isn't, please send mail to

Is App Tamer compatible with macOS 11.0 Big Sur?

Yes, App Tamer version 2.5.2 or higher is compatible with Apple's most recent Big Sur betas.

Which applications should I slow or stop with App Tamer?

You can use App Tamer with just about any application. It comes pre-configured for many common ones. For those that it doesn't handle automatically, follow these guidelines.

First, click on App Tamer in your menubar and see which applications are using CPU while they're idle in the background. Now consider what these applications do, and if they'll work just as well when slowed down or stopped. To change the settings for one of them, just click on it in the list.

Here are some things to consider:

  • The Finder should usually be left running because it provides services to a lot of other applications.
  • If an application performs a service without coming to the front, like Mail checking your email, you should slow but not stop it.
  • If an application receives notifications, chat messages, tweets, or other data from the Internet without you doing anything, it should be slowed but not stopped.
  • If an application floats windows above other windows to add features, as is done by Default Folder X, Drag Thing, or other UI utilities, they should be slowed but not be stopped. Also, their usability could be affected when they're slowed down. Experiment with different CPU limits.

To choose a CPU percentage for slowing down an app, set it as low as possible while not impacting your work. Some, like Spotlight, need to be given enough CPU to get their jobs done, so you may have to experiment a bit. App Tamer comes pre-configured with good settings for many of these.

Focus on applications that are using CPU when you don't want them to. And remember: if something "freezes" or doesn't work correctly, turn off App Tamer using its On/Off switch to see if the problem is due to an application being slowed or stopped.

How do I turn on Time Machine acceleration and how does it work?

You can make Time Machine backups run faster by choosing App Tamer > Preferences > Options and turning on "Accelerate Time Machine backups".

This changes a system parameter to allow Time Machine to run at full speed, rather than at the reduced I/O priority that it normally uses. Backups will complete much faster, but at the expense of taxing your Mac more, and possibly slowing down other applications that are running.

Also, be aware that turning on this feature can make other background processes speed up, too. It prevents the system from throttling any processes that are marked for low priority disk access, so it may cause increased heat and reduced battery life when iCloud synchronization, App Store downloads, etc are running.

For more information check out the articles at Mac Kung Fu and

App Tamer shows a notification every time it hides or quits an app. How do I turn those off?

You can turn Notifications off for App Tamer - or any application - in System Preferences. Simply choose System Preferences from the Apple menu, then click on Notifications. Click on App Tamer in the application list and set the notification style to "None".

What about macOS' App Nap feature?

Apple knows a good thing when they see it. Mac OS 10.9 Mavericks introduced App Nap, a feature that 's similar to App Tamer. But to activate it you have to hide or completely cover an application's windows, making it not-so-automatic. And App Nap doesn't work at all with behind-the-scenes applications like Spotlight and Time Machine.

App Tamer gives you control. If Spotlight is overheating your Mac and making the fans rev up like a fighter jet, for example, just select it and tell App Tamer to keep its CPU usage below 25%. If you want Chrome to use less CPU but still want to be able to glance at its windows in the background, just set its CPU limit to 2% with App Tamer.

App Tamer will not start up. It keeps saying it needs to install its helper application and asking me for the administrator password.

This happens when another application has installed a helper app into the folder "/Library/PrivilegedHelperTools/" and has given the folder the wrong security permissions.

The easiest way to fix this is to download an AppleScript we've created called "Fix PrivilegedHelperTools permissions". You can get it by clicking here. Just unzip the script application, double-click it, and type your administrator password into the dialog box that comes up. After doing so, you should be able to launch App Tamer and install its helper application successfully.

Stopped applications don't wake up when I click on them in the Dock. What's wrong?

Please run the Console application in /Applications/Utilities. Look for error messages like this one:

5/26/11 10:53:00 PM App Tamer[1874] event tap was disabled so I reenabled it

If you're getting these, the system is disabling App Tamer's request to be notified when you click in the Dock. When this happens, App Tamer won't restart stopped applications because it doesn't know you've clicked on them. This is most often caused by the Dock restarting. Some possible causes and solutions are:

  1. Some applications that modify the way the Dock works, like DockSpaces, do this intentionally to make the Dock reload its preferences. Because of this, DockSpaces and similar applications are incompatible with App Tamer.

  2. The Dock occasionally crashes because of a bug or corrupted data. If this has happened, restarting your Mac may fix things with App Tamer. If it was an isolated incident, you can just continue without giving it another thought. If it happens again, you'll have to figure out why the Dock is crashing and restarting on your Mac.

Thanks to Rick Stahlhut for tracking this down!

When an application is stopped, I get a spinning beachball cursor and the Dock says the app is not responding.

This is normal - because App Tamer completely stops processes, they do not respond to macOS' checks to see if they're running. As a result, macOS will display its spinning beachball cursor when you move the mouse over a stopped application's windows. Unfortunately, there's not a practical way for App Tamer to prevent this. Rest assured, however, that if you click on a stopped application's window, App Tamer will wake it up and it will respond normally.

How can I reduce App Tamer's CPU usage?

In normal operation, App Tamer should only use a few percent of your CPU. However, you can do a few things to reduce this even further:

  1. Close App Tamer's window if it's open. Updating and sorting the process list accounts for most of App Tamer's CPU usage.
  2. Increase the CPU statistics update time to 10 or 15 seconds (instead of the default 5 seconds) in your App Tamer preferences.

App Tamer is waking all my apps every time I click the mouse. What's wrong and how do I fix it?

There's a bug in macOS which causes it to get confused and start sending click notifications to App Tamer for every mouse click, rather than just clicks on the Dock. To recover from the problem, please do the following:

  1. Click on App Tamer's icon in your menubar.
  2. Find the Dock in the process list.
  3. Control-click on the Dock and choose 'Quit' from the menu. The Dock should restart automatically.
  4. Quit App Tamer and launch it again.

App Tamer has paused an app that's using 40% of my CPU, but the overall CPU usage on my Mac drops by 5%. Why?

App Tamer follows the conventions used by Apple's Activity Monitor so that there's consistency when you compare the statistics they report. This means that App Tamer represents per-process CPU usage as a percent of a single CPU core, while it represents overall usage of the machine (including the percentage shown in the menu bar) as a percentage of all available CPU power.

So when you look at the usage of an individual application or process, apps that are capable of using multiple CPU cores can easily use more than 100% CPU. If an app is fully employing 2 of the 8 processor cores in a modern MacBook Pro, it'll be shown as using 200% CPU. Confusingly, that'll only contribute 25% to the overall machine CPU usage (since it's fully utilizing 2 of the 8 cores).

So if App Tamer stops an app that's shown as using 40% CPU, that's 40% of a single CPU. If you've got 8 CPU cores in your Mac, that will only reduce the total CPU usage shown in the menu bar by 5% because that number accounts for all available CPU cores. Yes, it's confusing - App Tamer certainly wouldn't show things this way if Apple hadn't already set the standard.

What are App Tamer's default application settings?

Here are the default settings that come pre-configured in App Tamer:

  Adobe Bridge   stop
  Arq   25%
  Chromium   2%
  Dreamweaver   2%
  Firefox   2%
  Fireworks   2%
  Flash Player   stop
  Google Chrome   2%
  Illustrator   stop
  InDesign   stop
  Lotus Notes   stop
  Mail   25%
  Microsoft Edge   2%
  NetNewsWire   2%
  Photoshop   stop
  Preview   stop
  Safari   2%
  Spotlight   20%
  Spotlight Indexer   20%
  Time Machine   50%
  Time Machine Local   20%
  Word   stop


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Reviews and Comments
What a beautifully simple yet revolutionary App! But don't tell Apple that I can put off upgrading my Macbooks for another year ;)
- Marko Turner
It's "just working". Thank you so much. Love the product. Love the support.
- Gregory Morse
A) the user interface is completely intuitive, B) it seems to work perfectly and instantaneously, and C) I did independent confirmation with my usual tool (top from the command line) and astonishingly, Safari was sitting there firmly fixed at 0 %CPU. That is awesome!!! I am absolutely going to be telling everyone I know to go buy this immediately!
- Larry Yaeger
System Requirements
macOS 10.8 through 10.15

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