Efficiency mode on a Mac: how to slow down a background app

macOS has no Efficiency mode switch like the one in Windows Task Manager: nothing in System Settings or the Force Quit window holds one background app back. You can do it with Foreman, which has an Efficiency Mode for apps you need open but do not need right now: in the background the app runs at background priority and gets about a quarter of the processor time it would take, and when you switch back to it, it runs at full speed.

This post explains the idea, what macOS does on its own, how Foreman’s version works, and the cases where it helps and where it will not.

What Efficiency mode means on Windows

In Task Manager on Windows 11 you can right-click a process and choose Efficiency mode. Windows then lowers that process’s priority and runs it in a way that uses less power. The program keeps running, but it takes less from the rest of the machine. The point is a quieter, cooler computer and better battery life, without closing anything.

The idea fits anyone who keeps a lot open. A chat app, a music player, a sync tool or an old browser window all have to stay running, and none of them needs to be fast while you work in something else.

What macOS already does

A Mac is not blind to this. macOS has its own ways of managing background work. Apps can mark their own work as low priority, and macOS can slow down or pause work from apps you are not using. Apple silicon Macs also have efficiency cores that handle low-priority work.

What macOS does not give you is a simple switch for one specific app. If a background app is busy anyway, because of a badly written update check or a runaway page, there is no setting to hold it back. Terminal’s renice command can lower a running process’s priority, but it is easy to get wrong, it does not know whether the app is in front, and it is lost when the app quits. The Force Quit window cannot help either. Its only choice is to end the app, which is more than you want when the app only needs to stop hogging the processor.

How Foreman’s Efficiency Mode works

Foreman’s Efficiency Mode is for an app you need open but do not need right now. It works in two ways at once.

• Background priority. While the app is in the background, it runs at background priority. On Apple silicon that means it uses the efficiency cores, and its disk use is turned down.
• Short bursts. The app is also held to about a quarter of the processor time it would take, so it runs in short bursts.

When you bring the app to the front, it runs at full speed until you switch away. It also runs at full speed while it plays sound, such as music or a call. The rows read “Efficiency Mode” in the Processes page, or “Efficiency Mode, paused while in use” while it is running at full speed for you.

Some details that matter:

• It is remembered per app. The setting applies again the next time the app opens, until you turn it off.
• Menu bar apps and a few parts of macOS get background priority only, without the bursts.
• It works for anything running under your account. That includes many of macOS’s own background processes, such as Media analysis (mediaanalysisd), Photos analysis (photoanalysisd) and iCloud Drive (bird). It is not available for Foreman itself, for core parts of macOS such as kernel_task, launchd, WindowServer and loginwindow, or for processes owned by root, a system account or another user. Some macOS processes, such as nsurlsessiond and cloudd, run two copies, one under a system account and one under you, and only your copy can use it. The User column shows who owns a process.
• Quitting Foreman releases everything. All apps go back to full speed. If Foreman were to crash, a separate watchdog lets the slowed apps go.

The trial note: when the free 24 hours end and there is no license, Foreman stops reading figures, and anything it had in Efficiency Mode runs at full speed again.

How to turn it on and off

Select an app on the Processes page and click Efficiency Mode in the toolbar. You can also right-click it and choose Efficiency Mode, use the Process menu, or press Shift-Command-E. The apps using the most on the Performance page, and the menu bar panel, offer it too.

To turn it off, use the same control, on any page. The app runs at full speed again at once. If the selected app is suspended, the toolbar button reads Resume instead, since pausing an app is a separate action from slowing it.

When it helps

Efficiency Mode helps when an app is using more than it should for what you are doing with it, and you cannot close it.

• A sync or backup app that you want running but not competing with your work.
• A chat or video app in the background that keeps its processor use high.
• A browser with many tabs you want to keep, while you work in another app. How to tell if one browser tab is slowing down your Mac helps you find the cause first.
• A Mac on battery, where an app in the background draws more than you want.

How much it helps depends on how busy the Mac is. When the Mac has spare capacity, a background app holding back makes less difference, and there is no number to promise. It does the most when something is competing for the processor. How to stop one app from slowing down everything else on your Mac covers the wider approach.

When it will not help

It will not fix everything, so check the cause first.

• An app in front. Efficiency Mode applies to the background. The app in front runs at full speed.
• A problem that is not the processor. If memory is the trouble, slowing an app does not free any. A Mac that is short of memory needs fewer apps open, or a look at memory pressure.
• An app that does its work while you are away. A slowed app takes longer to finish background tasks. That is the trade.
• Something wrong with the app. If it uses a lot of the processor for no reason, restart it first, and update it.

A short routine

Open Foreman with Control-Shift-Escape, sort the Processes page by CPU, and look at what is high in the background. If it is an app you need open, turn on Efficiency Mode and see what the figure does. If it is an app you do not need, End Task.

Foreman needs macOS 14 Sonoma or later and works on Apple silicon and Intel Macs. It is $12 once for up to 3 Macs, and free for 24 hours from the first launch.