For the last three months I have been more or less enjoying my new late 2013 21" iMac. I already have an early 2011 MBP, which is pretty maxed out with a 512GB SSD and 8 GB of RAM, and still feels very, very fast.

The iMac has 8 GB RAM as well, but "only" the Intel Iris GPU and a 1TB SATA HDD. Both machines are running OS X 10.9.4.

Starting up a few apps, like Mail, Safari and maybe iPhoto, takes ages. Sometimes up to 20 or 30 seconds. Whereas the MBP takes only a handful seconds. It's clear to me that the SSD gives a great performance advantage. But is it really that much...?

I also noticed in the systems report that the Iris uses sometimes up to 1.5 GB of RAM. This seems like a lot. I imagine that this could also hurt performance.

I also get a lot messages like these in the system log:

24.08.14 19:57:32,827 WindowServer[539]: disable_update_timeout: UI updates were forcibly disabled by application "iPhoto" for over 1.00 seconds. Server has re-enabled them.

These happen if I switch from one iPhoto event to another, or switch to my iCloud albums. On the MBP this happens instantly, without delay.

Update: Here are some screenshots of the activity monitor and Console logging:

CPU load HDD load RAM usage Console logging

  • can you provide us with a screen shot of your activity monitor!
    – Ruskes
    Commented Aug 24, 2014 at 20:47
  • Can do that later
    – Arne
    Commented Aug 25, 2014 at 6:54
  • Added some screenshots
    – Arne
    Commented Aug 28, 2014 at 6:11

3 Answers 3


i've seen this on some of my machines... it is fixable (though ican't remember the details for my situation). but it will stay very slow until you clean out those ui/windowserver errors.

firstly: have you added any screensavers? have you safe booted to clean out caches and check HD?


  • No, but I will check this out.
    – Arne
    Commented Aug 25, 2014 at 6:54

That console message means iPhoto was doing so much processing on the main UI thread that it couldn't even supply updated UI to the windowserver for a few seconds.

It could be your iCloud Photostream acting up in iPhoto. I had this issue and had to disable photostream.


Upgrading to Yosemite did make things quite a bit better. It's still a bit sluggish sometimes, but overall response times are much better.

Also, the spotlight indexing took quite a hit.

  • One more thing: I opened a bug ticket with Apple and they said it was a botched Aperture library migration. However, I fixed it myself by re-installing the whole Mac. While at it, I added an external Thunderbolt-SSD to build a fusion drive. This was REALLY a good idea making the machine so much faster.
    – Arne
    Commented Mar 21, 2016 at 11:26

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