My two cents on this: The devs consistently spend time optimizing for “large” vaults, which is why the app almost doesn’t feel like an electron app. Given that it’s in beta, I would argue that optimizing now for millions of notes falls in premature optimization.
There are other features that are important for the sustainability of the app and other features that would make the app even better for the vault sizes we’re seeing today.
I’m not saying that this is not important, but it might be good to adjust your expectations on this. I’m sure it will come in time! If you do have some performance requests with large vaults, I’m sure the devs will appreciate more data points!