Perhaps it could make each request as you scroll? You don't need to see 1000 photos all at once. And if your friend has sketchy internet, perhaps it can push to you when they have a good connection.

It's not perfect, but if we want self hosted, we have to start somewhere and start working out the problems.

That would require javascript, and the set of people interested in self-hosting and the set of people willing to touch javascript with asbestos gloves and a ten foot pole do not intersect.