While I agree with the sibling that an hour's downtime isn't much, and that you can't expect much better performance than that, I'd like to give a shoutout to mailbox.org.
I originally chose them over Proton when degooglifying my life because of Proton's absolutely batshit crazy idea not to offer IMAP access. I've been very very happy with mailbox for years. Their web interface is ugly, but like I said… IMAP.
ProtonMail does client side encryption/decryption so there is no way to offer vanilla IMAP endpoints without some sort of client side decryption. This is what ProtonMail Bridge does. Although I'd admit it's not always the most stable experience, depending on your mail client.
It's still a completely pointless cludge, and another thing that can break. For no reason. No reason at all!
I really wanna like and use Proton. I think some of the people behind it are great. I wanna support Swiss companies (I miss the place dearly). I don't mind that it's a bit more expensive than many competitors. BUT I WANT IMAP ACCESS without some crazy converter stuck in between me and my email.
1) That's patently not true. It's their special flavor of encrypted email that's not compatible with IMAP.
2) I value IMAP far far far more than I value their special flavor of encrypted email. If they'd let me turn the latter off in exchange for IMAP without the crazy converter, I'd have chosen Proton when I was cutting Google out of emails.
I originally chose them over Proton when degooglifying my life because of Proton's absolutely batshit crazy idea not to offer IMAP access. I've been very very happy with mailbox for years. Their web interface is ugly, but like I said… IMAP.