[davidbalbert]

I had similar problems on my iPhone 7 when I upgraded to iOS 11. This included apps totally freezing, sometimes for what felt like a minute, with very laggy input, as well as other issues, like not displaying the playing podcast controls for Overcast on the lock screen or in control center. Yesterday I did a fresh install of iOS 11 and then restored from a backup and my problems seem to have gone away. At least for me, it seems like there may have been something wrong with the over-the-air upgrade process. Perhaps this will help you.

[4ad]

Hmm, that means redownloading 50 GB of photos, but I guess I could try it. Do you know if you could force download all the iCloud Photos library instead of having it load on demand? Even with Settings -> Photos -> Download and Keep Originals it seems old photos (from before the device was installed) are only downloaded on-demand. I want them all offline.

I'm having this problem on both my iPad (which is newer than my phone) and with my laptops. Old pictures are not there unless I view then, although new pictures seem to be pushed to all my devices. And even if I view then, they are downloaded only at medium quality, unless I view them for more than 1.5 seconds or I zoom into them. This means I can't even scroll quickly through them, as this won't get me the original quality I want.

[davidbalbert]

I don't take a ton of photos, so I don't know the answer to your question. Sorry :(

[stephenr]

Don't choose "optimise storage" and it will try to keep all photos locally.

[4ad]

It will try to keep new photos photos locally, but it doesn't seem to be downloading old pictures unless I zoom into them.