mediaanalysisd on Mac: what it is, why it is high, what to do

What mediaanalysisd does

Every time you point at a photo and macOS offers to tell you what the flower is, copy the text out of a screenshot, or find "receipts" in Photos without you ever tagging anything, that is the result of mediaanalysisd having looked at the image earlier. It runs machine-learning models on the device, not in the cloud, which is good for privacy and bad for your CPU: the work has to happen somewhere, and that somewhere is your Mac.

It analyzes the Photos library first, but not only that. Images in Finder that you preview, videos, screenshots, and on recent versions anything on a mounted volume that Spotlight can reach can be handed to it. It is a sibling of photoanalysisd, which handles faces, scenes and Memories inside Photos specifically. The two often run together after an import, which is why people see both near the top of Activity Monitor and assume something is broken.

It keeps a cache of what it has already analyzed in ~/Library/Caches/com.apple.mediaanalysisd so it does not repeat work. When that cache is behaving, it stays small. When it is not, it is one of the clearer signs something is wrong, as the section on when to worry explains.

Why mediaanalysisd is using CPU right now

1. You imported photos or videos. A camera card, a phone backup, a folder of scans. Each new item gets analyzed once. Video takes far longer than stills.
2. You updated macOS. New versions ship new models, and the library gets re-analyzed with them. Expect a busy day or two after a major update.
3. iCloud Photos finished downloading. On a new Mac, the library arrives over hours, and analysis follows.
4. The Mac went idle. This one surprises people. It is scheduled to run when you are not using the Mac. One user described it starting "after about 10 minutes of no interaction, using about 130% of the processor." You walk back to a warm laptop and assume it was busy the whole time.
5. A network or external drive with lots of images. On Tahoe in particular, people have reported that attaching a NAS or a large external volume sends it into analysis of everything it can see, which never seems to end.
6. A bug in a specific version. Sequoia 15.1 had a well-documented case where the cache folder grew to tens or hundreds of GB and the daemon stayed busy. Paul Hudson reported it "regularly been sitting on ~100% CPU for over a week now."

The first four settle. The last two are what the long forum threads are about.

What normal looks like, and what is not

How much work is left is the only thing that matters. Here is how long analysis typically takes on an Apple silicon Mac, plugged in and idle:

The healthy pattern: high while idle, drops to nothing when you start working, and over a few days the idle bursts get shorter until they stop. The stuck pattern: the same 100 percent every idle period, week after week, while Photos says it has finished. A Catalina user caught exactly that contradiction: "This is clearly a bug and is not working as intended, especially because Photos says it has concluded its face-searching."

Second check: Finder, ⇧⌘G, paste ~/Library/Caches/com.apple.mediaanalysisd, Get Info. A few hundred MB is fine. Tens of GB is the Sequoia bug; one report put it at "no less than 143GB" for a 27 GB photo library.

Is it safe to quit mediaanalysisd?

Yes, in the sense that nothing breaks. It restarts on its own and picks up where it stopped. No, in the sense that it achieves nothing: the queue of unanalyzed items is still there, and it will try again the next time the Mac is idle. Quitting it every evening is a ritual, not a fix.

What you should not do is the Terminal advice in older threads: unloading its launch agent needs System Integrity Protection off and comes back after every update. The decision tree below is the general rule.

For this process the useful lever is not quitting. It is deciding when it runs (give it a night on power) and what it can see (unplug the drive full of images).

What to do, in order

1. Open Photos

   While Photos is open in front of you, background analysis pauses so the app stays responsive. If you need the Mac quiet for a video call or a deadline, leave Photos open and the daemon backs off. This is the one-click option in the KB for a reason.

2. Plug in and leave it awake overnight

   Connect power, turn off sleep for the night (System Settings, Lock Screen, set "Turn display off when inactive" and let the Mac stay awake, or just leave the lid open), and let it work. 9to5Mac's advice for the macOS 26.5 version of this problem was the same: "connect to power overnight and let the machine get on with it."

3. Unplug external and network drives full of images

   If analysis started when you attached a NAS, a photo archive drive or a camera card, eject it and watch Activity Monitor for ten minutes. If CPU drops, add that volume to Spotlight's Search Privacy list (System Settings, Spotlight) so it stays out of reach.

4. Check Photos is not stuck itself

   Open Photos and scroll to the bottom of the Library view. It shows what it is doing: "Analyzing", "Updating" or nothing. If it says it is finished but mediaanalysisd still burns CPU for days, you are in bug territory. Restart first.

5. Restart

   Clears a daemon stuck on one corrupt video. If the next idle period is quiet, done.

6. Update macOS

   The worst versions of this (the Sequoia 15.1 cache growth) were fixed in later point releases. System Settings, General, Software Update.

7. Reduce what Photos analyzes

   In Photos, Settings, General, you can turn off Memories and Featured Photos and Siri suggestions. This trims the related work but does not stop Visual Look Up analysis. It is a small help, not a switch.

When to worry

mediaanalysisd is never a security problem and does not touch your photos themselves; it only reads them. The side effects are what deserve attention:

• Battery. Since Ventura it runs on battery too. If your MacBook loses 20 percent in an hour in your bag, this and photoanalysisd are the first suspects. The fix is to let it finish on power.
• Disk space. A cache folder in the tens of GB is the Sequoia bug. Updating macOS is the supported fix; the folder is safe to leave.
• Heat. Sustained analysis brings in kernel_task throttling on a laptop. Not harmful, but a sign to give it a night on a desk rather than a duvet.
• More than a week with nothing new. Then it is looping, and the usual cause is a volume it can see but never finishes: a NAS, an external archive. Unplug or exclude it. Safe to Quit records how many hours per day each process ran, so you can tell "finished on Tuesday" from "runs every night" without checking Activity Monitor at 2 a.m.

What is not a worry: an hour at 130 percent the evening after you imported a holiday's worth of video. That is the feature working.