What Is photoanalysisd and Why Is It Using CPU?

It is late, the Mac is on the charger, nothing is open, and the fan is running. Activity Monitor shows a process called photoanalysisd near the top of the CPU list, even though you have not touched Photos all day.

The short answer: photoanalysisd is the part of macOS that analyses your Photos library so it can build Memories, recognise People, and let you search for things like "beach" or "dog". It is designed to do that heavy work in the background, on external power, when the Mac is otherwise quiet. It is normal, it is safe, and it finishes on its own.

What photoanalysisd does

Apple's own manual page describes it as "the photo library analysis agent" and says it "handles background processing of photo libraries for Memories, People and scene or object based search."

It works alongside a few related processes you may also see:

On our test Mac, running macOS 27.0.1, all four ran under the logged-in user's own account, not as system accounts.

Why it runs at night, on the charger

macOS schedules this work deliberately, and the schedule is written in the agent's own configuration file:

/System/Library/LaunchAgents/com.apple.photoanalysisd.plist

For its main background analysis task, that file says:

• Run only on external power (RequiresExternalPower). It is not meant to drain your battery.
• Maintenance priority, and marked as resource intensive. It is background work, but heavy work.
• Allowed during Power Nap, and it prevents sleep while it runs. So a sleeping, plugged-in Mac can wake briefly to get it done, which is why you may hear the fan at night.
• Repeat roughly every six hours, after the face analysis from mediaanalysisd has finished.

So the pattern people notice, fans at night on the charger with nothing open, is the system doing exactly what it was configured to do.

Why it is busy right now

It has more to do when there is more new material in the library:

• You just turned on iCloud Photos, or signed in on a new Mac, and the whole library arrived at once.
• You imported a large batch of photos or videos.
• Your iPhone is adding photos through iCloud, so there is always something new.

The first pass over a large library takes the longest. After that, it mostly has new items to process.

Is photoanalysisd safe?

Yes. It is an Apple process and lives inside a system framework:

/System/Library/PrivateFrameworks/PhotoAnalysis.framework/Versions/A/Support/photoanalysisd

You can confirm the path and the account it runs under in Terminal:

ps -axo user,pid,pcpu,comm | grep photoanalysisd

A process with this name running from anywhere else would be worth investigating.

How to stop photoanalysisd (and should you?)

You can quit it, and it does stop. In Activity Monitor, select photoanalysisd, click the stop button at the top of the window and choose Quit. When we did the equivalent on macOS 27, it ended cleanly and macOS did not start it again straight away. It is launched when there is scheduled work, so it will come back the next time the analysis is due, and the work it had left will still be waiting.

That makes quitting a way to pause it, not to stop it for good. We know of no supported setting that turns photo analysis off.

What to do about it

• Let it finish. Leave the Mac plugged in after a big import or on a new Mac. Once the backlog is done, there is far less for it to do.
• Keep it plugged in overnight if you can. That is the condition the work is scheduled for, so it gets done while you are not using the Mac.
• Quit it if you need the performance right now. It will pick up again later, at a time macOS chooses.
• Repair the library if Photos itself misbehaves. If Photos is slow, will not open, or behaves oddly, Apple's Photos Repair Library tool checks the library's database. Back up your library first, quit Photos, then hold Command and Option while you open Photos and click Repair.
• Expect warmth, not damage. Sustained work makes a Mac warm and spins the fan. Our guide to why a Mac overheats covers when heat is worth worrying about.

See it in your menu bar

Because photoanalysisd runs under your own account, MacStats can see it. When the fan spins up at night, the MacStats menu bar shows the CPU load and its dashboard lists photoanalysisd among the busiest processes. With MacStats Pro, clicking it gives you a plain-English explanation of what it is doing and whether you need to do anything about it.

Find out what is running the fan before you start closing apps.

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Frequently asked questions

What is photoanalysisd on a Mac?

It is the macOS agent that analyses your Photos library in the background, so Photos can build Memories, recognise People, and search for objects and scenes.

Why does photoanalysisd run at night?

macOS schedules its main analysis to run only on external power, at maintenance priority, and allows it during Power Nap. A Mac left on the charger overnight is exactly when that work gets done.

Is photoanalysisd a virus?

No. It is an Apple process that runs from inside the system PhotoAnalysis framework. A process with that name running from anywhere else would be worth investigating.

How do I stop photoanalysisd on Mac?

Quit it in Activity Monitor if you need the performance right now. In our test on macOS 27 it quit cleanly and did not restart straight away, but macOS starts it again when the next analysis is due, so quitting only pauses the work.

How long does photoanalysisd take?

It depends on the size of the library. The first pass over a large library takes the longest, and after that it mostly processes new photos and videos.