Slow reboot after upgrading to OS X El Capitan I upgraded to OS X El Capitan a few days ago and was having issues with reboot and shutdown times. It could take up to a minute. So I cloned back OS X Yosemite from a backup and partitioned part of my SSD and installed OS X El Capitan to troubleshoot. Even on the partition OS X El Capitan still shuts down and reboots slowly. When it finally gets to the Apple logo it boots up fast.

Not that big of a deal, just was curious what was going on. OS X Yosemite works fine with no lag in reboot and shutdowns.



I have two boot volumes listed, El Cap that's on a partition, and Yosemite. I select the El Cap partition and it boots fine into El Cap after the restart. and when I'm completely shutdown and boot onto El Cap it boots fine, no lag. Its when I'm booted up into El Cap and do a restart or shutdown. That's where the lag is. I tried Verbose mode and when it started up, it did the white text on the screen then booted normally. I really don't know what I'm looking for here.
Here are few suggestions to troubleshoot the slow reboot issue:


After the system is booted, run:

sudo dmesg | less


and check for any errors.
Start up your Mac in safe mode (hold Shift after restart).
Start up your Mac in single-user mode (CMD-S) or verbose mode ( CMD-V).
Check for any suspicious messages in /var/log/system.log file during boot time. Or use the Console.app to check the logs during boot time.
Check the health of your battery using an app.
If you got any system crashes, please check for any shutdown causes.
Disable non-Apple kernel extensions (check by kextstat | grep -v com.apple).
Disable non-Apple services at startup (check by launchctl list | grep -v com.apple).
Make sure you don't use any custom boot arguments (check by nvram boot-args).
You can consider booting in verbose mode by: sudo nvram boot-args="-v".
Run Apple Hardware Test on your Mac (hold the D key during on reboot).
Book an appointment at Genius Bar and ask them to run the full hardware test using their macOS NetBoot Triage Image.