I have the following mac:

  • iMac (27-inch, Late 2013)
  • 3.4 GHz Intel Core i5
  • 8 GB 1600 MHz DDR3
  • NVIDIA GeForce GTX 775M 2048 MB

It has a HDD, and I have 240GB out of 1TB free space.

I'm on OS X El Capitan (10.11.3).

Since some time this mac has been very, very frustratingly slow. It takes about 15 minutes to go from a clean boot to getting firefox up and running. Especially starting applications is painful. It's a bit hard to quantify though, because at other times it seems ok. There's a big perception/psychology part to it.

I'm considering doing a fresh install, and perhaps go with an older OS X. But I'm also just extremely curious what's causing this. I can't figure it out. I know HDD's are slower, but the machine was fine when I got it, and I find it hard to believe that newer OS X's are so much worse.

Here's a few things I've done:

  • Turn off time machine, for good measure.
  • Turn off dropbox. My dropbox is rather large and I noticed it can be a pretty big factor when it's indexing.
  • I don't use FileFault.
  • 1Password is in the startup items, nothing more.
  • I recently did a scan of my disk in recovery mode, to ensure that the disk wasn't failing. S.M.A.R.T. says verified.

There's nothing out of the ordinary in Activity Manager / htop. CPU and Memory both seem reasonable. Also worth mentioning that if I start a game like Starcraft or Cities Skylines, these applications perform pretty well once started. Starting them takes a long time though.

I'm basically at a loss why my fairly new Mac is worse at running applications as back when I got my first white macbook in 2006, when the applications I'm running haven't changed (firefox, terminal, thunderbird), and Memory quadrupled.

I'm very comfortable with the command line, and I just want to satisfy my curiosity. What causes my computer to take 15 minutes to go from boot to Firefox? How can I measure what the computer spends time on? Are there maybe obvious performance improvements I missed?

diskutil list output:

/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *1.0 TB     disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:                  Apple_HFS Macintosh HD            999.3 GB   disk0s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3

A few (maybe) interesting items from system.log:

I got a bunch of these:

Mar 20 19:13:18 localhost kernel[0]: Sandbox: launchd(1) System Policy: deny(1) file-write-flags /private/var/run/dyld_shared_cache_x86_64h
Mar 20 19:13:18 localhost kernel[0]: Sandbox: launchd(1) System Policy: deny(1) file-write-unlink /private/var/run/dyld_shared_cache_x86_64h

A whole bunch of these for all my applications:

Mar 20 19:15:44 Pasta kernel[0]: Sandbox: coreduetd(74) deny(1) file-read-metadata /
Mar 20 19:15:44 --- last message repeated 23 times ---
Mar 20 19:15:44 Pasta kernel[0]: Sandbox: coreduetd(74) deny(1) file-read-metadata /Applications/App Store.app
Mar 20 19:15:44 --- last message repeated 4 times ---
Mar 20 19:15:44 Pasta kernel[0]: Sandbox: coreduetd(74) deny(1) file-read-metadata /Applications/Automator.app
Mar 20 19:15:44 --- last message repeated 4 times ---
Mar 20 19:15:44 Pasta kernel[0]: Sandbox: coreduetd(74) deny(1) file-read-metadata /Applications/Calculator.app
Mar 20 19:15:45 --- last message repeated 4 times ---
Mar 20 19:15:44 Pasta kernel[0]: Sandbox: coreduetd(74) deny(1) file-read-metadata /Applications/Calendar.app
  • The very first thing I would check is to see if your hard drive is failing. First, execute the command diskutil info /dev/disk0 | grep SMART If it says anything other than "Verified", then you drive is failing. I would also download DriveDX (free version) (binaryfruit.com/drivedx) and see what it says about your drive. Post the results to your question.
    – Allan
    Commented Mar 20, 2016 at 22:17
  • Also, if you could post the output of diskutil list .... just in case you are using CoreStorage and you have more than one drive acting as a single volume
    – Allan
    Commented Mar 20, 2016 at 22:22
  • Hi @Allan, added the output of diskutil list and the s.m.a.r.t. status was indeed good. But nervous about DriveDX, so I'm doing a bit of research to see what others are saying about it ;)
    – Evert
    Commented Mar 20, 2016 at 22:26
  • Just downloaded it. DriveDX doesn't report any problems. Most of the indicators are at 100%, and some at 85%.
    – Evert
    Commented Mar 20, 2016 at 22:29
  • Overall health is 85.5%. Doing the "quick" self-test showed no errors.
    – Evert
    Commented Mar 20, 2016 at 22:31

4 Answers 4


Your machine should not be this slow. If the below doesn't help, you can take it to an Apple store to run hardware tests. I've seen instances where faulty sensors, for example, would cause the computer to go into limp mode, and the hard drive was fine.

Have you tried resetting the PRAM?

There are some command line utilities that should be able to pinpoint what's using the disk (if that's the case). You can try iostat 1 - this will display general disk activity, refreshing every second.

To see more granular info such as the process, use "fs_fsusage": sudo fs_usage -f diskio

I'd first try to narrow down what's eating all the I/O using the above commands. You can always wipe and reinstall if you want, but if you restore your entire Time Machine backup, you'll be potentially re-introducing the problem. So I'd say only restore your data/ user account w/o the ~/Library folder if possible.

On the hardware side of things, these devices shipped with at least 7200 RPM drives. While much better than the slower 5400, modern OSes will still choke with excessive disk activity (spotlight, time machine, various system services).

Replacing the drive with an SSD on your own IS possible but you need tools, and have to be very careful handling the screen. So if you've never done it before I'd recommend paying someone to do.

EDIT: Also check your system log in Console... look for disk i/o errors


I know this is kind of a blunt comment, but after seeing your Mac specs, you really really should buy an SSD. If there is no other real problem (maybe there is) that is the single most obvious bottleneck I can see. ssds are fairly cheap now, so u can get a 250gb for well under 100$, and the hdd is easy to clone+ install, and your Mac will feel (and maybe be)5x as fast. If u still have warranty up u might have to pay a cert. Mac Tech tho.

  • It's an option I've considered, and I know it will likely solve the issue. but it doesn't address my main concern. Why does this computer perform worse than my 2006 macbook did essentially performing the same basic tasks. I'd like some proof that apple software really has become that much worse, and it's not some other problem. I prefer diagnosing the issue over throwing money at the problem.
    – Evert
    Commented Mar 21, 2016 at 7:03
  • While I am a big fan of getting SSDs, until you have narrowed down the root cause of your failure, you may be throwing good money after bad by simply throwing hardware at the problem. A boot time of 15 mins and a health hard drive could indicate a problem with the logic board; something that replacing your HDD with an SSD will never fix
    – Allan
    Commented Mar 21, 2016 at 11:20
  • You're right I guess. It's just that when I saw my mothers IMac 2014 boot up recently it actually felt like 15m (although its probably 2-3m) :D
    – evagreen
    Commented Mar 21, 2016 at 15:58

I ended up doing more searching myself, and came with a different solution.

Since CPU usage was fairly low, I figured it had to do with HD access. I used a combination of iotop and fs_usage to figure out who was doing what.

Turns out that Spotlight-related processes are pretty much busy all the time. That, and app store-related processes.

For now I killed the app store stuff, and added a lot of directories to the Spotlight exclude list. I pretty much just use Spotlight for launching applications, so I can probably live without it for the most part.

I'm going to see how this is going for a while. If it turns out that this solution is 100% fool-proof I'm closing this ticket, and the end of ~2 years frustration with crappy Apple engineering. But I'm waiting a bit, don't want jump the gun.


Running down "my computer is slow" problems is what keep IT & computer repair people in business as it is tough to narrow down.

Before doing much else I would be tempted to clone your HD to an external drive and then unplug it. Nothing like a well meaning maintenance routine doing something unexpected and hosing some (or all) of your data.

Not sure that zapping the PRAM is going to help with slowness issues, then again it can't hurt and only takes a few minutes, or in your case about 15.

I would run one of the maintenance utilities like Onyx or such. Go to the Automate tab, check all the boxes and let it do it's thing. Reboot when it is done and see what happens.

I would also boot into recovery mode and run Disk Utility and click on the drive and then repair to verify there really is nothing wrong with the drive.

If all of that does not work I would make sure you have a clone of your drive standing by, wipe the internal and reinstall the OS fresh. If it then boots up and is faster use the Migration Utility to copy your files and settings. I would be hesitant to copy the apps over as something there might have caused the problem (assuming migrating your settings didn't slow things down, then it is likely a preference file that is damaged or is putting the Mac in a strange state.)

Failing all of that then your choices boil down to an older OS that is not so resource intensive or a new SSD. El Cap. really does use all of the resources on a Mac: Memory & Storage to it's fullest so if it is choking a little on memory or utilizing the drive a lot those are potential slow downs and a faster SSD or more memory may indeed help the situation.

I have an older iMac with El Cap. and finally (because I didn't want to go through opening it up --what a mess--) I added an external Firewire 2 drive which helped the performance quite a bit. But internal gives you the best performance, your choice.

  • I don't get it, what's wrong with this answer? Commented Mar 22, 2016 at 14:32

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .