How about generating a 'cache key', encrypting it using nip04, storing it locally, encrypting locally cached stuff with it, and then when you reload - decrypting only that key and then decrypting all the cached stuff?
This is OK. But this extra complexity may not be worth it.
Currently I don't have a great use case for NIP-46 in Blowater yet.
Maybe the new Relayed relay implementation has a use case for it in the admin panel frontend.
The use case is that I won't paste nsec to blowater, that I can have restricted permissions, etc. And the complexity is probably worth it in terms of performance bcs you can use native encryption instead of nip04
What do you mean by native performance?
Oh sorry, I forgot nip04 uses browser-native aes