Q: CalendarAgent process is out of control - delegation may be causing problems?

What worked for me was opening Calendar, clicking on Calendars in the top left, unchecking all my Calendars in the list, restarting my MacBook Pro, and then opening Calendar again, clicking on Calendars in the top left, and rechecking those Calendars I wanted open (in this case only my Google Calendar). This may only be a temporary fix - I only did it 2 days ago but it solved the problem immediately.

Thanks bonzabuy! I had the CalendarAgent memory consumption problem after upgrading to Mavericks on my  late 2009 iMac. Your Calendar Cache file delete procedure appears to have solved the problem. Memory use stabilized at 22.0 MB. After I re-enabled my gmail calendars in Internet Account preferences, memory use rose to 26.7 MB and held. You have to be fairly quick about the restart. Otherwise the Calendar Cache file regenerates itself, I noticed. I don't know if that would prevent the fix from working.

Regards, davids11

This did it for me.   Full credit to  bonzabuy

on this thread:    Re: CalendarAgent process is out of control - delegation may be causing problems?

Jul 15, 2013 12:53 AM (in response to msl422004)

I spent over an hour on the phone with Apple support. They tried a number of things - from disk permissions, disk repair, start up items, login items, new user account.

This did it for me.

The thing that seemed to do the trick instantly:

Delete the Calendar cache.

A rough procedure:

Open iCal

Full back up all calendars (full archive I think it's called)

Close iCal.

Go to Finder

'Go" menu

Hold down option key

Go to Library

In Library go to Calendar.

Delete Calendar Cache.

Restart machine.

Start iCal.

If all is well & all reminders / appointments restored then you can delete the backup.

Hope this helps some others - it worked for me

My first fix was to simply quit the CalendarAgent using Activity Monitor. It started as 700K and slowly climbed back up to 59MB of Real RAM use. It seemed to stabilize there. I performed the suggestions posted here to uncheck the Calendar from the Internet Accounts preference (using Mavericks), deleted the Calendar itmes in the Library and CalendarAgent is stable at using 59MB of RAM, and 0% of my CPU. Thanks for the tips!

I used an application called calendar cleaner and it fixed it for me. I had to run the application about 5 times until it showed the desired results of "no conflict found". My calendar started synchronizing faster as well.

This works much faster:

OSX’s CalendarAgent can cause issues with processor/memory hogging from time to time. If you want to disable it yo can do so from the command line:

launchctl unload -w /System/Library/LaunchAgents/com.apple.CalendarAgent.plist

You can re-enable it with the following:

launchctl load -w /System/Library/LaunchAgents/com.apple.CalendarAgent.plist

You can test to see if it’s running with the following command:

sudo launchctl list | grep CalendarAgent

I am using MacBook Pro 2014 Retina Display. Initially came with Mavericks and upgraded to Yosemite (10.10.2).

Had the same Problem. Calendar Agent took nearly 6 to 7 GB of the RAM and left me with 15MB ram. Got really irritated. But found this after a hard struggle. I tried the above solutions, think didn’t quite work for me.

Follow the steps you will get your problem solved.

1. Backup all the calendar events to your iCloud by enabling calendar in the internet accounts from system preferences. (Do this step only if you need your events to be there).
2. Then open TERMINAL and type.
3. chflags nohidden /Users/*******/Library
4. ******* represents your username or the name in which your mac is started with. This name can be seen from "Macintosh HD” then “Users” then the user which you are..
5. After running the command then again type in TERMINAL
6. chflags nohidden /Users/*******/Library/Containers
7. Now close the TERMINAL after running it.
8. Now, open finder and goto "Macintosh HD” then to “Users” then the user which you are then “Library” then “Calendars”.
9. In “Calendars” you have got to delete some files.
10. Those are:

Actually after deleting it,restarting PC solves the problem.

Sometimes you can’t delete those files because the Calendar Agent uses them and is running in background.

For that you have got to open Activity Monitor and Force Quit Calendar Agent and delete.

Restart your PC. Then open Calendar. Nothing happens and is back to normal.

Thank you!  I changed my timing also and it seems to have helped a lot!