lack of snappy performance (as a critical aspect of user experience) is the #1 barrier to me recruiting more users to join me on Proton, even though (for me personally) the privacy of E2EE outweighs virtually any other factor.

Scrolling from week to week to see my events for the next few weeks keeps being slow in terms of load time. I find myself scrolling two weeks in advance and literally waiting 5-10 seconds for my events to show up again. Very inconvenient and makes the app hard to use. This is on Android.

Android calendar app is so **** slow :(

I've seen a couple people mentioning loading time when an app is opening, but a major weakness of Proton Calendar is that it's so slow to do basically everything and all other actions are held up until the one currently running is complete. Examples include initial loading of the calendar, creating a new event, changing the time on an existing event, modifying repeat sequences, etc.

I don't fully understand the technical aspects of what calls and actions need to occur, but other calendar apps such as Google Calendar and Outlook will perform most of these actions near-instantaneously. I know it's not simply network conditions because I have used both Proton Calendar and Google Calendar on a variety of devices and network conditions and there is always an obvious gap favoring Google's calendar over Proton's.

Comparing the Proton Calendar app on iOS and Android, the Android app is much slower. When you open the app, it flashes briefly while refreshing, and it takes a long time to load all the events.

It would help if more calendar events were stored locally, so that it doesn't take so long to display current events.

I exclusively use the Proton Calendar. Switching from other calendar apps over the years, Proton is by far the slowest to open. Almost all of my calendar interactions are when someone is waiting on me, and opening the app is very slow. I understand the app is doing an API call and I'm waiting during that time, but displaying a cached version WHILE the API call is underway so that I can begin navigation to the date I need would be amazing!

Sure, the data would be stale, but you could even grey everything out in the interum. Just being able to go to a date in question while it is loading would be a lifesaver!

I fully agree with Lilith: other calendar apps I have used so far load events in milliseconds. Achieving a similar performance would be a great improvement.

Worse here. It takes like 25s or more on the webapp (dekstop or iphone) to show the calendar.
I have to use the webapp because that's the only way to create an event in a shared proton calendar (feature not availabke in the ios app).

I have 5 calendars in my Proton Calendar view :
- the local calendar (mine)
- the one of my wife
- a shared one for the family (children activities, ...)
- birthdays
- my pro calendar (to avoid conflic when creating a personal event, for instance)

I would agree that loading events in the calendar app on a mobile device is very slow, and so is navigation within the calendar.
I am not keen on using the browser version as I like clearing browser cache all the time, but it's good that it is also available, and would like the same options available in both. The web version seems to have more.
I also use external calendars such as country holidays, but even if I disable these, it is still too slow.
Also the notifications seem slightly out of sync i.e. they often arrive a few minutes later. Probably due to the above.

Considering pretty much every other calendar app shows events with no perceptible delay after the it launches, I would consider fixing this an extremely high priority.

I agree that loading the calendar events, especially in the Android app, takes too long. Every week's events have to load for approximately 5 seconds. 2 seconds would be more reasonable.