Why your Mac stutters while you edit video or play games

A Mac stutters in video editing or games when something it needs, the processor, the graphics chip, the memory or the disk, is being used by something else at the same moment. Editing and gaming both need steady delivery of frames, so even a brief fight over a resource shows up as a hitch. The fix is to find what else is busy and pause it, close it or push it to the background.

Below: what causes the stutter, how to see which resource is running out, what to stop first, and how Efficiency Mode can quiet apps you need open but not right now.

What stutter actually is

A smooth picture needs a new frame on time, again and again. Games usually target a steady frame rate, and video editors have to decode and draw the frames of your timeline as you scrub or play. When a frame is late, you see a hitch. When many are late, you see stutter.

Frames get late for a few reasons.

• The processor is busy. Games run their logic on the processor, and editors use it for decoding, effects and exports. If another program is taking some of it, there is less for the job in front of you.
• The graphics chip is full. The picture is drawn by the GPU. A heavy scene, a high resolution, a big external display, or another app using the GPU leaves less per frame.
• Memory is short. Video projects and game assets are large. When memory pressure is high, macOS moves data out to the disk and back, and that delay appears as a pause.
• The disk is busy. Footage streamed from a slow or crowded drive can arrive late, and a game loading new areas waits for the disk too.
• The Mac is running hot. When a Mac gets warm, macOS slows the processor to protect it. The effect is a game that starts smooth and gets choppy after twenty minutes. Why a Mac slows down when it gets warm covers this.

On a laptop there is one more: Low Power Mode, in System Settings > Battery, trades speed for battery life, and it can be set to apply only on battery. If stutter vanishes when you plug in, check that setting.

See which one is running out

You do not need to guess. Start the thing that stutters, and look at the five numbers while it happens: processor, memory pressure, disk, network and GPU.

On macOS alone, open Terminal and run top -o cpu to see which processes use the most processor. It does not show graphics use, so it will only tell you about the processor side. System Settings, General, Storage will tell you whether the drive is nearly full, which hurts both editing and games.

With Foreman, the Performance page has a live graph for each of CPU, Memory, Disk, Wi-Fi and GPU, with a minute of history, and under each graph the apps using the most. Run your project or game, press Control-Shift-Escape (it opens Foreman from any app), and see which graph is high. The reading goes like this:

• GPU high and CPU low. The scene is simply heavy for your graphics. Lower the resolution or effects, close a second display or reduce the preview quality in your editor.
• CPU high. Look at which app is on top. If it is your game or editor, the job is heavy. If it is anything else, you found a competitor.
• Memory pressure high. Close other apps, because the project does not have enough room.
• Disk high. Something is reading or writing a lot, possibly your own project cache or a background sync.

If your game runs full screen, the menu bar may be hidden. In that case, play for a few minutes, switch out, and read the graph’s minute of history, which still shows what just happened.

Find and pause what competes

Most stutter caused by “something else” comes from the same short list.

• A browser with many tabs, one of them playing video or running a web app.
• Cloud sync catching up after you saved or rendered large files. The iCloud, Dropbox and Google Drive helpers all do this.
• Spotlight indexing after you created a lot of new files, which video projects often do. In Foreman this shows as “Spotlight indexing” and “Spotlight file reader”.
• Photos analysis after an import, shown as “Photos analysis” and “Media analysis”. It runs mostly while the Mac is idle, so it can be a surprise when you are not idle.
• A backup. “Time Machine backup” in the list.
• A chat or call app, especially with video on.

For the first group, closing is the simplest. For the parts of macOS, ending them rarely helps for long: they are doing real work, and many simply start again. Wait for them to finish, pause the job that started them (such as a sync) from its own app, or slow them down with Efficiency Mode, below.

If the app is one you want open but do not need during the session, you have options short of quitting. In order: quit it normally with Command-Q so it can save, then force quit only if it will not close. Or for an app that has to stay open, use Efficiency Mode.

Efficiency Mode for apps you need open

Efficiency Mode in Foreman is made for this case: an app you need open but do not need right now. While the app is in the background it runs at background priority (on the efficiency cores of an Apple silicon Mac, with its disk use turned down) and is held to about a quarter of the processor time it would take, working in short bursts. In front, or while it plays sound, it runs at full speed until you switch away.

So the chat app, the mail app and the notes app can stay open and leave more of the processor for your game or your export. Select the app in the Processes page and click Efficiency Mode in the toolbar, or press Shift-Command-E. It is remembered per app until you turn it off, so it applies again the next time that app opens. Turn it off from the same places and the app returns to full speed at once.

Two honest limits. It helps most when the Mac is busy and the background app was taking a real share, and it does less when the app is idle already. And it works on processor time, so if your problem is GPU load, lower the settings in the game or editor instead. Foreman does not promise a speed-up.

It works for any process running under your account, and that includes many of macOS’s own background processes, such as Photos analysis, Media analysis and iCloud Drive, which often wake up after an import or a render. It is not offered for Foreman itself, for core parts of macOS such as kernel_task and WindowServer, or for processes owned by root, a system account or another user. The User column, which you can add from the column header’s menu, shows who owns a process. Spotlight indexing and Time Machine backup run as root, so for those, waiting is the answer.

A short checklist before you start

1. Quit what you are not using, starting with the browser.
2. Plug in a laptop if the work is heavy.
3. Check the drive has free space (System Settings, General, Storage).
4. Put chat and sync apps in Efficiency Mode, or quit them.
5. Open the menu bar readout and watch it for the first few minutes.
6. If it is still choppy, lower the game’s or editor’s own quality settings.

How to stop one app from slowing down everything else on your Mac goes further on the competing-apps problem. Foreman is $12 once for up to 3 Macs, free for 24 hours.