Creating shared album takes long time I'm on iOS12, my wife is on iOS 13, she's in my family group. Today, I decided to share photos for the first time. On my iPhone 6, I went to the photos app and created a new album in 'shared albums'. Then I added 128 pictures to it. I then got a window with a pie chart saying "Vorbereiten..." ("preparing"). It has taken a very long time to complete this process, so I assume the images are physically downloaded and re-uploaded. 

Why doesn't icloud just give permission to the photos I share in my family group?
Files in your cloud count against your storage container and are stored there on the server.

Shared files don’t count against your allocation and are stored in different buckets with different QOS and technical details. 

Depending on if you optimize space on your device and have some items represented as thumbnails instead of the full images (or the image was modified on another device), you would have to round trip all 128 photos down to your device and then back up to the new bucket.

I’ve had preparing hang on one item, so I would cancel that and start with a single image, then add in a few and then maybe do the rest once you’re sure it’s not a server side issue.