Calendar very slow with macOS Monterey

Hi,

I have the exact same issue but I was able to narrow it down to my Exchange calendar.

If I disable it (and keep my iCloud calendar, my Google calendar, both US and FR holidays and Birthdays) it runs as fast as usual.

Julien

I have a very similar issue. It appears to be specifically related when using my work's business Google account. When thats enabled for calendaring, its beachball cursor time when moving from week to week/etc.

The problem goes away when I disable my work's business Google account disabled for calendars and still have all my other accounts (iCloud and two personal Google accounts) still enabled for calendars.

They were all working perfectly before the upgrade to Monterey.

Same issue here. Exchange influences this. If I uncheck it, no issues. Also happens for exchange based calendars that I reel in via Google (read-only). My Google calendars work fine. Arguably, they have a longer history than my exchange calendar. Don't fully understand, yet expect a fix.

I was having the same problem and tried turning off the Exchange calendar after reading your comment, and you were right! When it's turned off, it runs smoothly. When it's on, it might as well be an app from 2005. Unbelievable.. Hopefully this gets patched soon, because I need this to work in order to coordinate both my work and my private schedules.

Thanks for finding this out though! Very helpful, and I wouldn't have thought of it.

I've applied the MACOS update (Montery v12.1) and the IOS update (IOS 15.2) that seem to have resolved my performance issues with calendar on MACOS, and random jangling of the day view on IOS. (and slowness there, too)

For me at least the macOS 12.1 update has fixed the slow Exchange calendars issue.

Monterey update 12.1 finally brought relief.. issue seems fixed. thx

IT is definitely not an Exchange problem. It's also on iCal - it seems the amount of data is the issue. So if your Exchange calendar is the one with most entries the problem disappears if you unsubscribe. Same if iCal calendar is the one with most of your calendar data.

same issue.

if I disable the main Office365 calendar, it works fine again.

Unfortunately, that's my most important business calendar

12.1 seems to have solved it entirely.

I booted my Mac in safe-mode but Calendar still not working. If I unsubscribe to the Exchange calendar, Calender turn to work well, but I need to maintain it Exchange calendar subscription. Is it already planned a fix?

Although most commenters have noted the problem goes away if Exchange is disabled (my case as well), several said they had the problem and aren't using Exchange. The common thread seems to be large calendars. Most of us using Exchange have the bulk of our events on our Exchange calendar; hence, the problem goes away when exchange is disabled. Why Monterey is having problems with large calendars is a mystery. One can only presume the testers at Apple didn't test it with large calendars.

I spent 1 hour online with apple support on the same topic and we could not resolve it.

As others have noted it could be linked to large calendar content in general, as I was able to improve the speed by ‘unlinking’ one of my apple calendars (I have them split into Personal and Work).

ie. Disable Work events and it was running better.

Nevertheless, no solution from apple support and I don’t expect to see one, as I have had the same issues with my Apple Contacts also for the last 2 OS systems which started with Catalina. Spinning wheel and slow response. This has carried through to Big Sur and now Monterey also. I am sure that this is also linked to my large contacts files (I use a lot of images for contacts).

Updated my iPhone to IOS 15.2 and iPad is at 15.1 but no difference for Calendars.

The same is happening across all my devices including MacBook 12 inch and iMac 2015 which are running Monterey 12.1

Apple seems to be going backwards at every new OS. Have hidden my Calendar app and using Readdle Calendars on my IOS devices (it has always been my preferred app anyway) but Apple Calendar on iMac and MacBook is simply not usable.

According to Apple, no one has registered this a a problem that needs to be resolved…….

Thanks for this hint: it simply depends on how many events there are in the calendar, and it is unrelated to which calendar server is used, or whether anything networky is involved. Switching weeks does a lot of computation and produces nice spikes in Activity Monitor. It seems they managed to put some code into iCal that makes it behave behave O(n^2) or worse ... :-/

I had said this earlier: the issue is probably with the Exchange client or associated code (Apple libraries, etc.) being used by both the MacOS Calendar and the iOS Calendar app. It is not necessarily the Exchange server, per se. So, Fantastical might not be affected....

However, unless someone discovers something new, I think we are in a wait-for-Apple-to-fix mode so probably nothing more useful.