Slow boot time after update to Mojave - External SSD

Having read positive reviews on 10.14.3 solving this issue, I went ahead to download its COMBO update, and to my horror, it refused to install and update my external USB 3 Drive. The SSD drive is simply not selectable.

So I decided to try to update to 10.14.3 directly via Software Update instead, and it works!!

My iMac finally boots up swiftly like it used to.

I subsequently apply the 10.14.3 COMBO Update through the system, and this time it went through without any problem.

I'm glad the issue is resolved, for me at least.

Before 10.14.3, I was on 2-3 minutes between chime and Apple logo too, sometimes even longer. Now I'm back to about 7 seconds between chime and apple, just as it was before Mojave/APFS. Finally - THANK YOU Apple for fixing this utterly annoying bug at last!

@stevelawrencechch Check to see if you have selected your SSD as the Startup Disk in System Preferences.

You could fix that by combining the two drives to create a DIY fusion drive as I did. Then the OS decides what content goes on the HDD (internal) and the SSD (external) invisibly to you. It works like a dream now the Mojave update has fixed the bug that was causing this particular setup to 'go slow'. My five year old iMac feels like a brand new machine. It's a bit tricky to do - there are lots of online guides to doing it though. The main thing is you have to copy all your content, reformat the drives, then restore all your content. Is a bit anxiety-making in the process but I'm so glad I did it.

MacOS 10.14.3 Update.

From almost 2,5~3 minutes to:

- 27 seconds from pressing the power button to Apple logo and another 26 seconds to Login screen.

I repeated a few times and it's the same.

I can say that is better now.

Personally, I can live with this.

But there is room for improvements.

UPDATING Mojave 10.14.3:

(Imac 2017 - 3,4 GHz Intel Core i5 - 8 GB 2400 MHz DDR4 - Radeon Pro 560 4096 MB - Fusion Drive 1Tb)

Boot without any external ssd connected (ONLY FUSION DRIVE) = ~ 25sec

Boot with the FUSION DRIVE and connected sdd external (SAMSUNG T5 USB Type C - 1Tb) = ~ 47sec

Boot with SDD external (SAMSUNG T5 USB Type C - 1Tb) = ~ 47sec

There was an improvement with this update .. but there is still a lot to do in my opinion 😟

Hi guys,

10.14.3 update is here!!

Seems that it works!!

Seems 10.14.3 fixed it here!

;-)

Same here! Works perfect now, boots pretty fast now with inateck enclosure, ssd samsung 850evo.

Would be interested what caused the problem? Apple didn't mention this fix?

I've noticed that after Mac OS mojave update, version 10.14.3 my boot time has decreased to 20sec.

Before that update my boot time were 2 minutes too.

Hope this will help

Oh wow so happy. Finally getting the performance I was hoping for when I created a DIY fusion drive using an external SSD to put new life into my late 2013 iMac. Startup has gone from 2 minutes plus to 20 seconds. Feel like I have a new computer!

Well, I've just gone backwards.

My MacPro - With OS on the INTERNAL drive and an externally connected SSD with APFS and used as a home directory has gone from 1 minute to 3 minutes 48 boot time.

Most of the extra BEFORE the pre-boot kernel is loaded (I boot with verbose mode so I can see what it's doing). For slightly over 3 minutes from the chime that all is fine I just have a blank screen while my MacPro contemplates how to take over the universe by boring me to death

Here's the situation after updating my external SanDisk 2TB USB SSD to 10.14.3:

Takes 35 seconds from the point where I click Restart in the Startup Disk control panel inside System Preferences to where I first see the Apple logo. I could hear the standard volume boot chime during that restart. It then took about a minute until it rebooted again, this time with a softer boot chime (akin to what you hear during firmware updates), and it finally booted to the Desktop, taking a total 2 min. 35 seconds (measured from the point at which I clicked the Restart button). Had there not be a stupid dual reboot sequence, it likely would have taken only 1 minute 35 seconds total.

This is all the reason why I have Mojave only on an external drive as a test. I am still running rock solid High Sierra on everything else. In my eyes, Mojave is still very much a bag of hurt.

OK, but 3-4 MINUTES between the chime and the Apple logo compared to now 47 seconds for the WHOLE boot process really IS a big improvement if you ask me! You'll always have to accept a certain time sink when booting from an external USB device instead of the built-in Fusion or SSD drive, typically something like 10-15 seconds. If you want to eliminate this too, then you have to retrofit your iMac with a built-in SSD upgrade, I think.

It's not booting from an external SSD that I have an issue with. It's the fact that booting is slow if there is an external SSD connected that has been APFS formatted.

There is no booting from external SSD required to hit this bug. Just have an APFS formatted drive attached and you will get the same thing.