Why is people scanning in MacOS Photos so slow?

Try this:

1. Export all your photos from your library as full-sized photos, choosing either TIFF or PNG formats, not JPG (JPG loses information in the compression). This full export might require time to download whatever is missing from iCloud, but it ensures that no photo information is lost. It also will detect any corrupt photos etc.

2. Create a brand new empty Photos Library. This library will be disconnected from iCloud. That's fine, leave it that way.

3. Import all your photos exported in step 1 into the new library. Scanning will resume and for me 27,500 photos completed in four days at an average speed of 271 photos per hour. :-)

You will lose all albums in this process of course, and all tags too. For me it was worth it.

You are right, I forgot to mention that you lose the originals with my method. I still have the original library but plan to trash it soon as I have no reason to revert my edits to any original versions and I am willing to give up those albums I made in exchange for a Library that is clean and does not have any corruption.

If you prefer a "lossless workflow" you could export the originals in step 1 instead of the edited versions. However, then you lose your edits by definition. Unless there is some way to repair the original library, I'm satisfied with my method. As I said it loses some information. Shrug, after all this time, I'm happy to just be back on track. All I care about are the dates and places primarily. I've already lost the face data a long time ago.

It is a trade-off. I'm glad you found a way to get your library working again.

It is a pity that Photos does not have a way to help us to isolate problematic photos or videos. A simply warning message telling us which photo or video cannot be processed or is currently processed would help, and we can remove them from the library.

Why - no one here can answer, only Apple knows why anything

it is slow and it is doing a log - My older iMac finished in about two days, my MBA is not finished yet - just keep the computer awake and powered and I quit hotos and it will finish someday

LN

The "Optimize Storage" is slowing it down. Photos needs to download the photos from iCloud for scanning.

It is quicker for the photos that are already stored locally.

. But I leave it and leave it and it gradually creeps up. Sooooo slow.

And as long as it is making progress let it run.

One problem with Sierra is, that we have quite a few reports about a dropped internet connection, and then it cannot download the photos. Do you also notice problems with the internet?

I have even more photos than the OP and I store mine locally but also use iCloud photo library. it is just as painfully slow here with a very fast internet connection. 23,000 scanned out of 62,000 images in the last 7 days. it has now been stuck (with many reboots) for the last 3 days at the same number. Frustrating to say the least.

All my photos are stored locally. I upgraded to Sierra "day 1" and I have around 20,000 photos. It is not finished yet ! It remains 196 photos to be analyzed since yesterday morning without any progress in the meantime. I am just wondering if is frozen !? He could be fine to be able to run manually this analysis...

I have this same issue. My cell phone and MBP are both synced with iPhoto and both use optimized storage. I have about 18,000 pictures. My phone is done the processing and my MBP still has about 7,000 more to do and has been sitting at that number for over a week. I have done reboots and that didn't help. I've turned off sleep settings so it's always on. Doesn't help.

For my MBP:

I upgraded to Sierra on day 1. I've had it charging a lot! For example, last night I had it charging for over 12 hours, and it processed 11 photos... really? That's just too slow. What's the issue? My only guess is that they are storing the facial recognition data server side, and their servers can't keep up. Can anyone confirm that guess?

For my phone:

When I updated to iOS 10 on day 1, my phone took about 2 weeks to process them all. But that's largely because I didn't have it plugged in charging during the day. Whenever it was charging it would always process at a pretty steady pace.

it has now been stuck (with many reboots) for the last 3 days at the same number. Frustrating to say the least.

Do you have videos in the Photos Library? The progress will be much slower, while the videos are scanned for faces.

But what I still don't understand is why iOS did the whole lot so much quicker. Or does iOS not scan videos like MacOS?

I don't know - I have not found a single video with a face assigned on my iPhone, and the user guide does not mention the videos in the section about the People album: http://help.apple.com/iphone/10/#/iph9c7ee918c

Just had a quick search and found a video on my iPhone that has been identified with my face.

That is good to know. Thank you.