Doing a "high-performance" decentralized lookup of hundreds of Nostr profiles is very, very hard to do.

Many lack Relay Lists, many have massive amount of relays, many don't have their profiles published on all their relays.

Many keep stale and dead relays in their lists.

It becomes impossible to ensure a very good experience, it will be an best-effort and sometimes fail the first attempts.

Hopefully as people user Nostr more and Nostr clients helps users maintain their Relay lists, this will improve in the future.

Here is one way to improve in Nostr clients: Make sure that your client broadcasts Relay List/Following List/Metadata whenever the user modifies their relays. Ensuring that any Nostr clients can pick a smaller set of relays when they attempt to retrieve that important data for the health of the network.