Why Your Mac Gets Slow After Importing Photos (and What to Do)

You came home from a vacation, plugged your phone in, imported 2,000 photos, and now your Mac feels like it’s wading through mud. It’s hot, the fans are running, and basic apps take forever to launch. This is Photos doing exactly what it’s supposed to do — and it’s unfortunately CPU-expensive enough to wreck your day.

Here’s what’s actually happening, why it can run for days, and how to manage it without breaking the features Photos provides.

What Photos does after every import

When new photos enter your library, the Photos app spawns a process called photoanalysisd (you can see it in Activity Monitor). It does several things:

1. Face detection and recognition — finds people in photos, groups by face
2. Scene classification — identifies “beach,” “mountain,” “food,” etc.
3. Object detection — recognizes what’s in each photo for search
4. Memories generation — builds curated highlight reels
5. Geographic clustering — groups by location
6. Quality assessment — picks “best” photos for various uses
7. Thumbnail generation at multiple sizes

For a single batch of 500 photos, this takes maybe an hour. For 10,000 photos imported all at once, it can run for days. For a freshly migrated 100,000-photo library, it can run for weeks.

Why it pegs your CPU so hard

photoanalysisd runs the same machine learning models your iPhone uses, on every photo. On Apple Silicon Macs with Neural Engine, this is fast but still significant. On Intel Macs, it’s brutally slow because they don’t have the same hardware acceleration.

The process tries to be polite — it backs off when you’re actively using the Mac, runs harder when you’re idle, prefers AC power. But on a busy library or a small import that piles onto an already-busy queue, “polite” still means using meaningful CPU all day.

There’s a faster waySweep handles this automatically and lets you approve before anything’s deleted. Try Sweep free →

How to tell if Photos is the cause

Open Activity Monitor (Spotlight: “Activity Monitor”). CPU tab. Sort by % CPU descending.

If photoanalysisd is at the top, that’s your culprit. It can sit at 100-300% CPU (multiple cores) on Apple Silicon, or 90-100% on a single core on Intel.

You’ll also see related processes:

• photolibraryd — the main library service
• mediaanalysisd — system-wide media analysis
• cloudphotod — iCloud Photos sync (separate from analysis)

If multiple of these are pegged, you’re in the post-import storm.

What you can actually do

Option 1: Wait it out (the right answer for most people)

For typical imports — a few hundred to a few thousand photos — letting it finish takes hours, not days. Plug your Mac in, leave it on overnight, come back in the morning. By morning, it’s usually done.

Option 2: Quit Photos to slow it down

photoanalysisd runs more aggressively when Photos is open. Quit Photos and the analysis pauses or runs at low priority. You can resume work, then reopen Photos overnight.

This isn’t documented behavior — Apple doesn’t say “quit Photos to slow analysis down” — but in practice, it works.

Option 3: Disable Memories and analysis features (nuclear option)

You can disable face recognition and Memories in System Settings → Photos → Memories. The analysis still runs to some extent for search and basic features, but the heaviest work stops.

You lose: Memories, “People” album, face-based search, “On This Day” features.

You keep: basic Photos functionality, search by date and location, syncing.

For most people this is too much to give up. For a 2017 Intel iMac that grinds to a halt every time Photos runs, it might be worth it.

Option 4: Don’t import all at once

If you have a huge backlog (say, importing years of phone photos), import in batches of 1,000-2,000 over multiple days. Each batch’s analysis finishes before the next one queues up. The Mac stays usable.

Storage implications

Each imported photo also generates:

• Multiple thumbnail sizes
• A preview image
• Cache files
• Index entries

On a 5,000-photo import, expect 1-3GB of additional space used beyond the photos themselves. Photos manages this reasonably well, but it’s worth keeping in mind if you’re tight on storage. The library can balloon faster than you’d expect.

Apple menu → System Settings → General → Storage will show Photos as a category. If it’s grown massively, the analysis is also using cache space.

iCloud Photos complications

If you use iCloud Photos, every imported photo also has to upload. Watch Activity Monitor for cloudphotod process. Network and disk activity stay high until upload completes.

If your library is set to “Optimize Mac Storage,” Photos starts removing local copies of older photos as new ones come in to keep total size manageable. This generates additional disk activity.

For huge imports, expect Mac performance to be impacted for the duration of upload, which can be hours or days depending on connection speed and library size.

Why your Mac is hot

Sustained CPU work generates heat. The Photos analysis can keep CPU usage high for many hours. On MacBooks, that means fans on (or thermal throttling on fanless Airs). On iMacs and Mac minis, the same. On Apple Silicon Macs, the chip handles heat well; on Intel Macs, it can trigger aggressive thermal management.

If your fans are loud and you can feel heat, that’s normal during import processing. It’ll subside when analysis finishes.

Make this a one-click jobSweep does the same hunt in seconds. Always shows you what’s about to go. Free for macOS →

The first-time-ever scenario

If you just signed into a fresh Mac and connected to iCloud Photos with a 50,000+ photo library, expect:

• Days or weeks of sustained background analysis
• Significant disk space used as photos download (if not optimized)
• Mac performance impacted throughout the day
• Battery life shorter than expected

This is unavoidable. The library has to be analyzed once. Subsequent imports are manageable; this initial pass is not.

The best strategy for a fresh setup: don’t import or sign into iCloud Photos until you have a few uninterrupted nights to let the Mac process. Plug in, leave on, come back in 3-7 days.

What photoanalysisd doesn’t do

Worth being clear: photoanalysisd is not “Photos uploading to iCloud” or “Photos backing up.” Those are different processes. The analysis is purely local, building features that work even offline.

Even with iCloud Photos disabled and no backup running, importing photos triggers the same analysis cost. There’s no way to import photos to your library without paying this CPU bill.

When it’s actually broken

Rarely, photoanalysisd gets stuck — running constantly for weeks without making progress. Signs:

• CPU pegged but progress indicators in Photos don’t move
• Analysis still running 2+ weeks after a moderate import
• Photos app crashing repeatedly during analysis

Fix: quit Photos, restart the Mac. If still stuck, try rebuilding the library:

1. Quit Photos
2. Hold Cmd+Option, then launch Photos
3. Choose “Repair” when offered

The repair takes hours but resolves stuck states. Back up your library before doing this — it’s safe but invasive.

Bigger picture

Photos analysis is the cost of having a smart photo library that surfaces faces, places, and memories automatically. It’s why you can search for “dog” or “beach” and find photos. It’s why Photos can build a “Memories” video of your weekend.

For most people, the trade-off is worth it. The slowdown is temporary; the features last forever. Just budget the time after a big import.