The CalendarAgent service takes all my CPU, every time I get a network connection. This is really annoying in many situations (one example: closing the lid for 2 minutes, change train and open it again) and slows down everything.

I already tried many solution:

  • reset the calendars
  • clear the cache files
  • change configs for the accounts
  • renice the CalendarAgent process
  • set ALL my accounts to manual refresh (Command + R)

The service doesn't care; if it's active it will hog the CPU. Only alternative is to disable the service; but, what a surprise, the Calendar app won't work anymore and crash.

I have calendars in sync with iCloud, Exchange, Google.

I'm struggling with this issue and would really like to take control back on this annoying process. I am fine with having to refresh manually the calendars but at least decide when to hog the CPU with updates.

How can I solve this?

OSX: El Capitan

  • try to disable synchronization to test defaults -currentHost write com.apple.syncservices SyncingDisabled YES change it back with NO ...Alternatively just disable calendars one by one to see which one is doing it – Ruskes Sep 30 '18 at 20:16
  • It still pops up after 1 minute the network/wifi connection is enabled and takes a lot of CPU. It seems to run a little shorter, at least, but the undesired behaviour is still there. I really don't understand what it is doing, and also don't get why it ignores my "update manually" setting... (if Syncing is what it is actually doing, during those CPU bumps) – Kamafeather Sep 30 '18 at 20:35
  • did you disable all calendars and it stops ? – Ruskes Sep 30 '18 at 20:41
  • I disabled all of them now: it still hogs the CPU but for shorter time now (around 10 seconds). I suppose that syncing is just part of the problem; it is doing also something else. I really would like to get this service to run just once per-day; I don't need this continuous updating/operations. To notice: it always spikes (but for shorter) also immediately after disabling the network/wifi. – Kamafeather Sep 30 '18 at 21:00

I had the same problem with El Capitan, High Sierra, and now Mojave (seems to have worsened). For me the removing the google delegation seems to have solved the issue: How can I diagnose or fix the CalendarAgent occupying a whole CPU on Mountain Lion?

  • Yeah all that piece of software sucks. And there is not a single decent alternative, free of charge, on the AppStore. I cannot get rid of the Google calendars, those are my main ones! 🙁And Exchange ones for work. And... even removing the Google ones it is still sluggish, spikes at 100% every single time I get a network connection or wake from standby...... I am seriously looking to get totally rid of CalendarAgent process and find some alternative/**working** software... – Kamafeather Jan 23 '19 at 14:00

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