It would greatly improve the user experience if the different processes could be done with an optimistic feedback. Meaning that the process should assume the operation will succeed and proceeds with executing it immediately, rather than waiting for confirmation of success before moving on.

A good example would be when deleting an email. Currently, Proton waits for it to be processed before updating the UI, which makes the UI sluggish. We even see a blank screen for a few seconds before displaying back the list of emails. It could be snappier if the UI was updated right away and process the request in the background.