I've recently updated my 15-inch, Mid 2010 Macbook Pro to Mavericks. Since then, it's been running incredibly slow and tends to hang while using programs such as FireFox or Excel.

If I look at the activity monitor, the only task taking up a large amount of resources is kernal_task.

I've verified the hard drive through disk utility, and it said that the drive is fine. Here's the hardware overview, if that helps:

Hardware Overview:

Model Name: MacBook Pro

Model Identifier: MacBookPro6,2

Processor Name: Intel Core i5

Processor Speed: 2.53 GHz

Number of Processors: 1

Total Number of Cores: 2

L2 Cache (per Core): 256 KB

L3 Cache: 3 MB

Memory: 4 GB

Processor Interconnect Speed: 4.8 GT/s

Boot ROM Version: MBP61.0057.B0C

Does anyone know what could be causing this?

  • Do you have any kind of Virus scanner ruining? What does it show as Memory load in Activity.
    – Ruskes
    May 16, 2014 at 16:44
  • No virus scanner. Memory load is at full, though the only large task is the kernal. May 16, 2014 at 16:52
  • Did you do a clean install of Mavericks? How much free disk space do you have? In the Activity Monitor, which process(es) are using more CPU time? May 16, 2014 at 17:22
  • Maybe its the spotlight indexing? Check this by click on the spotlight icon in the upper right.
    – Mathias711
    May 16, 2014 at 19:37

1 Answer 1


As Mathias711 pointed out in the comments, the cause of this was Spotlight automatically re-indexing after the after the OS upgrade. The process of indexing was greatly slowed down by OSX attempting to index a very slow, old external drive we had hooked up.

Once the indexing had finished (it actually took quite a while) the laptop eventually returned to its former speed.

There's also a post by Computer World that backs up this conclusion:

OS X will rebuild the Spotlight index after a major System upgrade. The process takes time and degrades performance while it takes place.

Click on the Spotlight (looking glass) icon to the top right of the display to see if indexing is taking place. If indexing is in progress you should see a dot in the middle of the looking glass icon and/or be told the operation is taking place. Allow the process to complete and you should see immediate performance improvement.

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