Proton Calendar horribly slow


my mum has a Fairphone 3+. It has never been a very fast phone, but it was fast enough for most purposes until now. The Proton Calendar app, which she has recently installed, is extremely slow, though. Clicking on any day causes a load of at least 10 seconds, often more like 30 seconds, or even over a minute. It probably takes longer the more days one clicks on.

I’ve checked a couple of things on her phone to resolve this. Storage isn’t an issue, memory usage looks fine, and there also aren’t any suspicious background processes running. I’ve restarted the device waited a while and started Proton Calendar afterwards, without opening any other apps, same issue.

On my Pixel 3 it usually doesn’t take longer than 2 seconds for a day’s events to load.

I’d like to know if anyone here has tried Proton Calendar on an FP3 and had a similar or hopefully a better experience.

You say that but Iyou provide no detail :slight_smile:
Do you have 10Gb free on the internal memory?
Do you use an SD card and how have you formatted it?

Free storage is more than 11 GB and there’s no SD card in the device.

I’ve also tried disabling Wi-Fi. Same result.

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You may want to try starting in safe mode, which disables all the apps and then just enable Proton Calendar, it may indicate a conflict.

Just downloaded to a laptop, will install later.

By the way I use Simple Calendar, maybe that is worth a look. Via F-droid

Ah, I didn’t know it’s possible to enable third-party apps again in safe mode. I’ll try this tomorrow if I get the chance.
Thank you for your help!

I’ve just installed but see it requires an online account, which I never use, so have unistalled it :frowning:

I think you may be right in that it isn’t possible, :slight_smile:

I just tried it on my FP3 and Proton Calendar is not slow at all. Opening a day or adding an event works very smoothly.


Hi felschr

I´ve just installed it on my FP3 and got no such delay issues.
Changing days or adding/deleting entries work within seconds.

Just guessing what could be a reason for that it´s so slow on your mom´s device:

  • maybe there are already dozens/hundreds/thousands of entries which could slow down the device - or is it still slow while being freshly installed and w/o any appointments?
  • not sure if Proton Calendar uses the cloud or is only local on the device but if it´s a cloud solution then maybe the upload/download could be a bottleneck on your mom´s device? Tried it along with a stable and fast Wifi connection ?


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Thank you for trying it on your phones, @HolosericaCaligo & @DonFnord.
Most days have multiple events, but I wouldn’t say it’s an excessive amount, though.
Can you maybe create one or two daily recurring events to see how it performs on your phone then?

I’ve tested it with my Pixel 3 on the same Wi-Fi network, so the network itself isn’t the problem. I’ll try running a network speed test on my mum’s Fairphone next.

Not sure what you consider a fast phone and wondering if there is anything “wrong” from the beginning, because I would not say at all its slow. I dont play any exessive games and everything else like Browser, calendar, WA and so on works without any issues for me. Have you installed any “special” security “features”? Which OS is installed? Any Google deactivated?

A roughly “total number” instead of this statement would be better. :wink:

Even if it does not have much entries per day: How much time back do ALL calendar entries go? Is there probably a history of several years with some/several entries per day ?
This could be a very good reason for the slowdown.

Try setting up a clean separate calendar as test. if this works fast you got the bottleneck :wink:


PS: Please keep in mind: Proton Calendar is a heavily encrypted app/service. The more (recurring) meeting you have in the past and even in the future the more hardware ressources is needed.
Seems like this is affecting not only FP users but also other devices; see: .
Maybe Proton already tweaked their app round about last year but I´m getting more and more confident that you should do a test with a fresh and empty calendar on your mom´s device. I expect this should work fast(er).


She has imported all events from Google Calendar. I’ll try removing imported events from her account for now. That’s a good idea.
Not sure why I haven’t found that Reddit thread before :sweat_smile:.

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Glad it helped and thanks for sharing that result :wink:

I’ve just cleared the app’s storage (not just the cache) and rebooting fixed it. It’s much faster now! :partying_face:


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