Settings for CalendarAgent, Mingler and iCalExternalSync services
It's a bit of a workaround, but these unload commands seem to do the trick. I put them in a script that I run when I need more of my CPU:

#!/bin/bash
launchctl unload /System/Library/LaunchAgents/com.apple.AddressBook.SourceSync.plist
launchctl unload /System/Library/LaunchAgents/com.apple.CalendarAgent.plist
launchctl unload /System/Library/LaunchAgents/com.apple.syncdefaultsd.plist


For when processes are acceptable, replace "unload" with "load"