My calendar app has become super slow (possibly after the OS X 10.10.4 upgrade). Every action, like clicking on a calendar item or scrolling to the next week, will result in approximately 60 seconds of OS X beachballing. The app syncs with 8 different calendar servers (webdav, google, exchange, and ical). This usually works very well.

I had this issue some years ago but forgot how to fix it. Any ideas?

  • what calendars are linked to it ? – Ruskes Jul 3 '15 at 6:20
  • @Buscar웃SD: I updated the question – n1000 Jul 3 '15 at 6:24
  • This is happening to me as well after the latest El Capitan update, though it's been doing it since Yos. If I try to make a new event, it takes upwards of 2 minutes just to open the dialog, then it takes about 45 seconds to record each keystroke when I type the subject. 45 seconds... per letter. – Cyprus106 Oct 26 '15 at 18:01
  • I had a variety issues with my SMC, disk permissions, reconfigurations, and with bloat after the most recent upgrades... it could be a bunch of stuff. I'm not sure what your issue is from what you have said... it would help to have an idea of what hardware you have (HHD/SSD for memory? RAM amount? Etc.) – sas08 Dec 19 '15 at 4:01
  • same problem. Started after mojave upgrade – Stefan Papp Oct 16 '18 at 7:37

The first step is to make a new user account.

  • Does calendar app itself contain the problem with no calendar data?

Then you can isolate things from the network. Pull any wired networks and power down WiFi and restart. Retest calendar in the test account (which presumably is always fast and responsive) and your account (which is slow now).

Once you've done that, you can enable networking, sign out of your account and add your calendar source data one by one (if you maintain several calendars in OS X) to the test account to tell if your data is slowing the app.

Assuming you have a speedy calendar in the test account with your real calendar data - you can conclude that your caches for the data was the cause of the slowness. When that happens, I usually move everything over to a new account since the corruption in one app is almost always shared in another.

To make sure the disk isn't causing further issues:

  • delete the calendar data from the test account
  • make a full backup (if you like) as well as a Time Machine backup
  • restart the Mac to recovery HD to repair the volume with Disk Utility (or do a safe boot which runs the same filesystem check)
  • use the test account to remove the old account - keeping the files on disk (don't erase and don't make an image of the home folder when asked)
  • make the normal user account and then use that to move back the data from the old home folder
  • 1
    All this to speed up the calendar? Seems a bit much, doesn't it? I mean I could reinstall regularly but I'd prefer not to. – Alper Jul 5 '18 at 21:10
  • I agree @Alper, but if your machine hangs for 60 seconds at a time, that’s a pretty severe denial of time to work. There’s no good way to triage this other than being methodical or paying someone else to be methodical about it. – bmike Jul 5 '18 at 22:59
  • I have only a couple of Google accounts that it syncs with so for me at least part of the solution is to use different clients to the same data. – Alper Jul 6 '18 at 8:07

I solved my slow calendar by turning off Birthday calendars, Holiday Calendar, and Siri Found in Apps Calendar in the Calendar preferences.

I noticed an immediate improvement in speed. I restarted Calendar and the speed improved even more.

I suspect the slowness came from the birthday calendar feature. I have 5,787 contacts and that causes slowness elsewhere. I noticed Calendar app RAM usage went from about 300MB to about 100MB after turning off the special calendars.

calendar preferences

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