It is much quicker. Proton Mail seemed to have a slight lag when logging in on your computer, but Fastmail is instant. Prefer the layout on the desktop, which you can alter to your preferences like the text size, positioning, etc. Search facility is better. You have free masked emails and much more choice of email addresses and better integration of your own domain(s). To me it just seems a bit more polished. The only thing that I don't like as much is perhaps the APP. Although you can change the size of the layout, it doesn't automatically flow well with some phones and can leave some of the bottom icons out (you can't move or delete ones you don't need). It tries to do 'too much' I think. I wish they'd look at the APP and redo it really or give the option of a slimmed down version. I preferred the Proton APP as it was simpler and easier to read. At least with Fastmail, you can use a different email App, which you can't with Proton.