While traveling this week (MacTech 2016 Conference) I found that my Mid 2014 MacBook Pro Retina’s battery life was down to less than 2 hours, and the fans were running all the time. A quick look at the Activity Monitor revealed that a process named secd was using up over 90% of the CPU.
Force quitting secd resulted in it respawning, continuing to hog the CPU. I rebooted and the problem persisted. Next I reviewed the system.log and run fs_usage through the Terminal, and found odd references to keychain. In the past I would have run Keychain First Aid in the Keychain Access utility, but that feature was removed by Apple in Mac OS 10.11.2, and my Mac was running 10.12.1.
So next I googled to see what secd was all about, and found a couple of hits describing my same problem. The workaround posted was to turn on Keychain in the iCloud system preference pane. I was skeptical this would help, as my Mac wasn’t even logged into iCloud, but sure enough I logged in and turned on Keychain, and the secd process stopped consuming all my CPU.
Upon further research this seems to be a bug effecting many people. I’m sure it happened on my Mac after upgrading to Sierra, but I didn’t notice it at first because normally I run plugged into power and it’s common for my fans to be on because I run VMware Fusion and Adobe CC apps frequently. I also found you don’t actually have to turn on Keychain in iCloud complete, you just have to check it then uncheck it.
Here’s a growing Apple discussion thread on the subject.