Ever since rolling out the 10.6.7 update on my latest MacBook Pro (15", i7), I have found that Mac App Store has become awfully slow. Starting it alone takes anywhere from two to four minutes for the application to become functional and start responding. During that time, the application seems to get lost into the 'not responding state', with the spinning beach ball showing up.

I looked into the output of Console.app, hoping to find any clues as to what's going on. I found a series of entries to the effect of:

5/6/11 1:55:58 PM   [0x0-0x95c95c].com.apple.appstore[16533]    Fri May  6 13:55:58 mbp App Store[16533] <Error>: CGBitmapContextGetBitsPerComponent: invalid context 0x100610e10
5/6/11 1:55:58 PM   [0x0-0x95c95c].com.apple.appstore[16533]    This isn't a bitmap context. Forcing destination format to ARGB_8 for CGContext.

What is strange is that I have a late-2009 white MacBook model which is booting the same version of OS X: 10.6.7. Mac App Store loads quickly on that machine. However, in the output of Console.app on that machine, I also see similar errors. I am wondering whether these errors have anything to do with the sluggish behaviour of Mac App Store application on my MacBook Pro (clearly, it works fine from the sluggish point of view on my slower, older white MacBook).

If you require any specific, particular information, I'd be more than happy to provide it. I'm looking for any insights, clues as to what is going on, and what I can possibly do to fix it.

Many thanks.

  • is there any difference in the network setups between the two computers? dns settings maybe?
    – robzolkos
    Commented May 6, 2011 at 9:11
  • 2
    if you installed 10.6.7 via software update, you may want to try downloading the combo update from Apple and apply that. This is a larger download as it contains all updates from 10.6.0 onwards, but it sometimes seems to work better than the differential updates in the software update process.
    – barryj
    Commented May 6, 2011 at 9:29
  • +1 for the question, I also noticed that the MAS was a lot slower
    – Agos
    Commented May 6, 2011 at 10:20
  • +1 @barryj - The Update Combo, although over 1 GB in size now, is worth trying. It's the only way I ever update point releases these days as the auto-update program does have a tendency to muck things up I've found. You won't do any harm, and you may fix your problem, by applying the Update Combo.
    – boehj
    Commented May 6, 2011 at 10:23
  • Hi RobZolkos. They are both on the same network, behind the same router. I'm using Google's DNS on both, but I've tried without it as well.
    – ayaz
    Commented May 6, 2011 at 13:02

4 Answers 4


Did you by any change change the Certificate settings in Keychain Access?

If so, that's the source of your problem. Go back to Keychain Access > Preferences > Certificates and turn Certificate Revocation List: off.

The Mac App Store should be snappy again after that.

  • Interesting. :) That did solve the problem. I turned Certificate Revolcation List to Best attempt, following some security best practices advice a few months ago. I can't remember where I read it from. Anyhow, having it turned off does make it work as it did before. Kudos and many thanks!
    – ayaz
    Commented May 25, 2011 at 21:23
  • I did that too, can't remember where either. But it had something to do with some Comodo certificate being corrupted or something. Commented May 26, 2011 at 7:57
  • You're right. It was after that Comodo ordeal, when malicious certificates were issued to certain popular companies and later revoked.
    – ayaz
    Commented May 26, 2011 at 10:34
  • Unreal - great catch Loïc - it's sad that there is no indication of the certification check delay in practice so as to not punish people for being more secure.
    – bmike
    Commented Jul 1, 2011 at 15:40

The App store is basically an XML parser that uses webkit to process html5/css/javascript. Focus on your network and differences between macs that work well and those that are slow. It's likely having problems getting the content from Apple's servers.

The usual suspects are overcomplicated or corrupt network preferences, DNS servers that are slow or misconfigured, other runaway processes or interface problems. Do check wired or wireless connection that is different than the one you usually use in case you have a hardware issue - but you should see equal issues in iTunes app store / safari as well.

The only obscure thing is if your installed product database was somehow corrupt and the MAS is churning trying to figure out what is already installed either locally or for your account on their server end of things.

You may have to sample the app or profile the network to poke deeper. If you are up to poking deeper, Daniel Jalkut stumbled upon a debug menu for the MAS app. He notes that "nobody knows for sure what these options do, and you might do serious damage to your Mac or your App Store account by playing with them" so I would urge caution. Looking or logging the XML or clearing cookies should be harmless.

Have you asked Apple for support? I consider anything that prevents iTunes or MAS from working a billing issue since I want them to be able to bill me for my next purchase!

Lastly, have you verified the date is correct on the troublesome mac?

  • Thanks, bmike. I switched the connection from AirPort to Ethernet, flushed the DNS cache, and used ISP provided DNS instead of the Google DNS that I was using on both the systems. However, I could not notice any improvements (other than the mere few seconds). Naturally, if MAS was taking too long to load content, I should think that the Network Activity Indicator would keep spinning. But it disappears after a few seconds, and the mouse cursor turns into a spinning beach ball.
    – ayaz
    Commented May 9, 2011 at 5:52
  • Well - it's looking more like an account or local install database issue if it's locking up but either not hitting the store with the correct request or if the request from the store causes your MAS to spin. Testing malformed data is very hard - so if the XML files being processed are buggy, you could easily end up in loops. A real puzzler without being able to debug the payload.
    – bmike
    Commented May 9, 2011 at 14:40
  • Hi bmike. I am wondering whether it will be helpful to flush and reset the MAS settings/preferences and cache. I have not done that yet. I remember reading about flushing the preferences for Spotlight in order to fix a bug in MAS where it wouldn't show any of your installed/purchased applications.
    – ayaz
    Commented May 12, 2011 at 8:20
  • hard to tell - i'd say experiment if you are sure you can recover from a backup of your mac and live with it or call apple support if you need this machine to keep working.
    – bmike
    Commented May 12, 2011 at 15:33

I've had exactly this problem about 10 minutes ago, on 10.6. Even the console.app logs were the same! I applied the combined upgrade, as I had an older version of 10.6, and yet the problem appeared.

My first idea was to upgrade not only OS X, but also Safari and apply all the other updates that Software Update suggested (except iTunes). Then the computer restarted and App Store started working properly, installing applications without freezing up.

So if somebody comes around with this problem, I recommend to try installing all the updates first. Let me know if that helped you also!


If you use Googles DNS servers, then you will find that they direct to servers which may not be as geographically close to you as if you were using your own ISPs dns servers. This is a known issue and affects load times of both the App Store and downloads from iTunes.

To determine if this is in fact the case:

  1. Open the Mac App Store whilst using googles dns server and time how long it takes.

  2. Change your dns servers to your isp ones and flush your dns cache in terminal using the following command dscacheutil -flushcache

  3. open the Mac App Store and time how long it takes. Should be significantly quicker.

  • Thank you for your reply, RobZolkos. I did just that. Apart from an improvement of a couple of seconds, I did not notice anything else. The MAS kept on beach-balling and going into "Application Not Responding" state for a while every now and then before responding.
    – ayaz
    Commented May 9, 2011 at 5:50

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