I don't buy this theatre for 1 second. Proton obviously has the ability to run a data business off my data if they wanted to - they own it all and it runs on their server.
Not saying they do it, but the idea that it's impossible because of "encryption" is a joke - you assign the keys and you could easily use them on the backend out of my view, the user has no visibility into how that works or what you guys do behind the scenes - it's not like decentralized technology (even the best decentralized tech can't deliver on this promise yet).
So it seems like it's slow because of client-side encryption which Google also does. Yes I know they have a data business, but the data is still encrypted.