How can I speed up photo sync on my iPad?

Cromiriark wrote: Those are the 2 options. iCloud or finder/cable?

Actually, you can have Finder do the "syncing" over wifi rather than by using a cable. That's what I was asking.

It seems very weird to me that syncing with a cable would take as long as you're seeing. Do you have at least 10% of your storage free on your Mac and on your iPhone?

It the storage is OK, then the first thing I would so is, rather than using Finder on the Mac, I'd use the app Image Capture that's in the Applications folder. I would use that to upload pictures from the iPad to folders in Finder, and then I'd drag them to Photos.

It's worth while to do a Forced re-start on your iPad:

Force Re-start iPad

This is different from a simple Power Off. I had to continue holding the button down past the "slide to power off" message, and then I released the button only after  the Apple Logo appeared indicating a re-start. 

 To narrow things down, try these steps on the Mac:

• Restart the computer (of course)
• Re-start in Safe Mode. This bypasses certain potentially disruptive processes, and it often helps. Safe Mode is different for different computers, so see this: 

           Start up your Mac in safe mode - Apple Support 

Those are the easiest things to try first. Then try these:

• Use another library if you have one, or make a small test Library with a few pictures in it and see if the same thing happens. You can create a new Library by closing Photos and then option-clicking on the Photos icon. To do the "syncing" you would need to designate this new Library as the System Library. Let us know if you need help with that.
• Make a new user and see if the same problem recurs with it.  This is a bit harder, because a new user can't access a different user's stuff. You would need to either create a new Library for the new User, or move your Library out of your own user's folder up to the general "Users" folder. 

Are you using wifi rather than a USB cable?

I use iCloud to synchronize my phone and Mac, and edits usually sync immediately, less than 3 seconds. But sometimes it takes a long time-- I assume because something on the Mac or phone is really busy.

Since syncing uses the battery, and since lots of people are very anxious about battery drain, the iPhone will avoid syncing when not plugged in. And since syncing uses processing power, and people hate slow downs, the iPhone will avoid syncing while you're using it. And since syncing requires bandwidth, the iPhone will avoid syncing when the internet connection is weak.

So, if you want faster syncing, then find good wifi, plug the phone in, and leave it alone. All this applies to a lesser extent for the Mac.

If I really need to move an image quickly, I use AirDrop.

Oops-- you're talking about transferring pictures to your iPad, not the other way. So wifi is not an option, and neither is Image Capture. Storage is still a good question. Force restart the iPad still applies. And it wouldn't hurt to restart the Mac in Safe mode.

Cromiriark wrote:

I have 40,000 photos on my Mac. So selected albums using finder and a cable to sync.

I have a similar size Photos library and also I sync it via Finder & USB to the iPad.

Sometimes a simple looking sync with only modest changes in an album or album selection might take hours and sometimes it seems to stall for hours in the "finishing sync" phase. And sometimes it syncs quite fast (usually a tiny few image change in the library causes hundreds of files reported to be synced in the progress but I guess the database structure needs that).

Finder & USB sync to the iPad has always been flaky (as were old similar iTunes sync). I just created a new library from scratch but at the moment numerous images and movies still fail to sync to the iPad despite repeated syncs.

I have all originals archived on external HDDs in plain Finder folders (one folder per "album"), and I plan to try if sharing them from an USB-C SSD via iPad Files.app straight to the iPad's Photos might be more robust. I just briefly tested this in a small scale and it worked OK but I must test the whole workflow and how to handle possible updates in "albums" with more detail later.

Matti Haveri wrote: …sharing them from an USB-C SSD via iPad Files.app straight to the iPad's Photos might be more robust.

Outside of iCloud, I think using a drive to transfer files makes the most sense. I thought that the Lightning cable made using an external drive awkward, but USBc has made this way easier and more sure. I haven't seen anything that would make me trust using Finder with a cable to transfer files.

Richard.Taylor wrote:

USBc has made this way easier and more sure. I haven't seen anything that would make me trust using Finder with a cable to transfer files.

iTunes/Finder USB sync is easier (...if it works) if the user already has a Mac Photos library albums, especially with Photos-updated metadata, that s/he wants to sync to iPhone/iPad.

Via USB-C/Files.app sharing it is not so straightforward. The user must export plain images and movies from Photos library to an external USB-C drive, and then Share them from there to iPhone/iPad Photos. ...metadata updated inside Photos, as well as the very old Photos .xmp bugs are flies in the ointment for that workflow... I plan to test this later.

Matti Haveri wrote: … iTunes/Finder USB sync is easier (...if it works)

You're right, of course. For transferring Library to Library, using a drive won't work. I didn't think it through-- I only use the drive to transfer files, and I'm just so happy that it works that I forgot the whole point. Duh.

How frustrating! It seems like, if PowerPhotos can transfer pictures between Libraries on a Mac, that Apple should be able to get it to work reliably between Macs and Phones. They certainly get it to work over the internet.