I have a MacBook Pro (I think mid 2012). About three months ago it started running really slow, so I renstalled the OS with a recovery partition. For a few weeks it ran very well with an overall very seamless experience.

Yet, as of two days ago, suddenly it started running extremely slow again. When I use vim and save a 200 line text file it takes about a minute average. When I want to click an icon or menu bar, it's not unusual to delay even highlighting the widget for 30 seconds.

I thought it might be the hard disk drive, so today I changed to a brand new SSD. This, however, had no effect.

The computer runs at this very slow speed even when system monitor says that there are 1.5GB RAM left and 97% idle CPU.

Does anyone know what the issue might be?

Right now I’m trying to run the recovery partition again, yet even booting from it has already taken me longer than writing this.


I have only used about 30 GB of my startup disk.

I am not aware of any malware, yet, I canot be sure.

I have 4 GB of RAM (DDR3 1600MHz)

CPU is i5 2.5 Ghz


I got it into recovery mode, and even here it's painfully slow, even if I select a disk i disk utility, it takes quite some time to even highlight the name. Could a reinstall even do the trick here?

More clear details

Computer specifications:

MacBook Pro 13" (mid 2012)

CPU: 2.5 GHz i5

RAM: 4 GB 1600MHz DDR3

Graphics: Intel 4000

Disk: 500GB (now 120GB) Only 30 GB when running slowly.

No retina.

OS: Mavericks, it came with Mountain Lion (It has run well with Mavericks)


As suggested I tried to replace the Hard Drive cable following this post.

The cost of this was the cable itself (around 32 EUR), and was done with only PH0 and PH00 screwdrivers.

It's been working perfectly for around 30 minutes with no sign of the prior slowdown. The repair was very easy and the effect is just as one could wish for.

  • 1
    do you have any virus software installed
    – Ruskes
    Mar 20, 2015 at 20:13
  • Please edit your question to provide clear/specific details on how much space you have on your hard disk drive, how much RAM you have and other basic details. What about free space on your disk? You say you moved to a new SSD, but how much free space do you have? Also, how much RAM do you have total? Mar 20, 2015 at 20:15
  • You edited but you only say you used 30GB of the drive but you are not clearly stating what the full capacity of the drive is. Please provide very clear details. Mar 20, 2015 at 21:37
  • Which OS are you using? And which specific model of MBP are you using? Is it a 13" i5/4GB/500GB HDD non-retina model by any chance? Mar 20, 2015 at 21:38
  • If you got a solution, please do not insert it into the answer, post your own answer and accept it, you might expand the ` following this` part to make it useful for future readers (keeping the link as reference)
    – bummi
    Mar 25, 2015 at 16:01

1 Answer 1


Hard drive cable failure is almost guaranteed to be your problem. We have a deployment of around 70 2012 13" MBPs for staff members, of which around 10% have had a hard drive cable failure. I had a suspicion you were going to say you had the same model from the symptoms you described.

The symptoms on our problem MacBooks are exactly the same as yours with the MacBooks running excruciatingly slowly on the most basic of operations. Replacing the cable has restored full speed without any further work needing to be done. Simply re-seating the cable's connector on the logic board has worked on a couple of occasions - in the short-term - but these have generally slowed down again, sometimes completely failing.

The odd thing is some of these MacBooks haven't been subject to any abuse and the cable has showed no signs of damage. However, the simple fact is that replacing the cable has worked.

The cables are available online (genuine cables can be had at a reasonable price on a certain auction site) and can be changed in under 10 minutes. The fiddliest part is disconnecting and reconnecting the IR receiver/status LED as there's a tiny latched connector to undo, but otherwise it's an easy fix.

  • This is is very releaving for me to hear! Would I need special tools, or will simple screwdrivers do the trick? Mar 21, 2015 at 7:25
  • 1
    A good quality set of Philips screwdrivers like the C.K. T4896 set will be all you need. The case screws ideally need a Philips-00 size driver (smaller than than you expect but seats and grips better than a Philips-0), the hard drive cable is secured by a couple of tiny screws needing a Philips-00, and the hard drive mounting brackets need a Philips-0. There are four case screws with a shoulder section, remember these go at the edge nearest the trackpad. Buy an airduster can as well, you may as well clean up the fan and blow away dust that's stuck in the heat-pipe radiator at the back ;-) Mar 21, 2015 at 10:21
  • 2
    You were absolutely right, changing the cable solved the issue! Mar 25, 2015 at 15:59
  • 1
    Is there a way to test this in software to diagnose it as the cause?
    – yincrash
    Oct 3, 2015 at 19:39
  • 1
    Thanks, this worked perfectly! I was about to pull my hair out. The Apple Hardware Test was passing (even the extended one) and new different HD didn't fix it. The cable was the trick.
    – sflogen
    May 9, 2018 at 3:33

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