If people want nostr to be fast and usable on slow phones and connections, ship client features that compress all data. Even with local db, nostr uses a lot of memory to render large images and cpu to play unoptimized images and all of this has a large impact on battery, or so Xcode tells me.

Centralized apps handle all of this for users and is why they are fast and energy efficient. We have to do this in a decentralized way by doing our part and disrespecting lazy clients.