The biggest problem I see right now is the first use experience. The first 15 minutes you use a product determines whether you continue using it or likely drop it forever.

When you just start #Nostr & you wanna see anything, all Relays have to be queried first, etc. At first, everything is empty.
Happens as well, when you delete the cache of the #Nostr app you use.

People are so used to instant access, it's probably a pretty big blocker to wait for Relays to finish loading the feed, especially in Global, basically like viewing an image in Internet Explorer during 2003.