I think the only win you can really get then is using a compact note format like nostrdb’s to fit as many notes into memory as possible and use that as the note representation instead of js objects. Still pretty horrible though.

That could be a benefit if the client chooses to keep GBs of events in-memory. Blowater actually plans to "never" delete locally. Many web clients still don't treat on-device storage the main storage and query from relays everytime. I believe local-first approach is the only way to have decentralization product-wise and to have fast client tech-wise. Therefore, I like nostrdb's motivation a lot. But what will be nostrdb's query interface? Function calls? Query languages? Can it answer questions such as what's all my notes which have been replied within 2 hours of creation? I would love to see a nostr "database" that provides graph algorithm queries.