The proxy Pablo made is a good solution. Not everyone will run their own node but it could be offered as a temporary service for those travelling with data restrictions. Although, battery consumption is also a reason to optimise.
nostr:npub1l2vyh47mk2p0qlsku7hg0vn29faehy9hy34ygaclpn66ukqp3afqutajft brought up in this interview that one of the big problems with Nostr he acknowledges is the fact it is very data intensive which translates to cost on mobile networks.
I'm trying to get him interested in adding something to the base protocol that could drastically reduce the amount of network chatter between relays and clients, reducing cost, time and energy. I'm not a developer though so I don't know how to do this through the proper channels, please talk to me if you want to take it forward.
Discussion
Proxies belong tight with Fedi instances; it’s the same threat model.