Q: Why does v10.11.6 boot up so slowly?

Does your computer have an SSD or a hard drive? A spinning hard drive is much slower and may cause boot times to be slower. Can you estimate how long it takes to boot?

Five or six seconds sounds unusually fast to me. Was that in Mountain Lion?

Anyhow, as an experiment you can try to start up in verbose mode: How to start up your Mac in single-user or verbose mode - Apple Support

Watch what is happening during that startup, and make a note of steps that are strikingly slow.

Do you have many entries in the SystemPreferences->Users&Groups->LoginItems ? take them all out.

Pleyel wrote:

 

Thank you for your reply.  I'm running an iMAC (early 2009) with a hard drive.  I updated to El Capitan about two weeks ago, and it takes between 20 and 23 seconds to boot up.  Before updating it took five to six seconds to boot up.

FWIW, I agree with Esquared. I have owned/used Macs for 31 years. None of them would boot in 5 to 6 seconds. From powered off to the desktop takes 14-15 seconds for two of my laptops that are pure SSD. My 2015 iMac which uses a Fusion drive takes approx 20 secs. Most of that difference is because the iMac has 4 times the RAM it has to check on boot.

p.s. the iMac also has 3 external drives to mount.

20 seconds to boot up on a mac with a rotating hard drive is excellent.

I would so far as to say that is too good to be true.

I have to wonder if you actually mean boot up (i.e. the time your mac takes to start when you press the power button) or something else.

If you can, please be specific. Is this time from power button to login window? (If so, it is great, no reason to complain)

Do you have auto-login and is this time from power button to desktop? (If so, halelujah! it is amazing)

Mine are booting up in 10-15 seconds (sata SSD), the Pcle drives in the newest macs are faster than that...

I never had a HDD mac that was faster than 30 seconds...

Luis and Lex reminded me of something. My Macs are all set to Auto Login. And if I ever had a HDD Mac boot in 5 to 6 seconds I would think it was broken, or possessed.

I never have a Device set to autologin, so the login is included in my times above

Interesting. It would take me 5-10 seconds just to type my password.

getting old

I simply don't believe it was ever 5 to 6 seconds, and that it is not now is normal.

So you were not talking about boot time at all.