I just bought myself an iMac 27'' late 2012 model.

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I am constantly getting beach balls and the computer slows to a crawl taking anywhere from 30 seconds to a minute to get back to regular speeds.

My normal programs are:

Rubymine Parallels Desktop Chrome Skype

I've used a laptop with less specs than this iMac and it never had these terrible hiccups. What can I do verify what is causing the issue?

8GB is more than enough for what I'm using - is it just the Apple-tax that requires me to have even more ram?

  • 2
    Ok, you do have a problem, but for us to help ypu we need to see 1-your activity monitor screen shot, your console screen shot. Meanwhile to test, run it in Safe mode to exclude non apple apps causing it.
    – Ruskes
    Commented Nov 15, 2014 at 23:39

5 Answers 5


It might help to examine how the machine's resource usage looks inside of Activity Monitor...Are the CPU cores maxed out? How about RAM usage - is there any green showing in the pie chart? Lastly - is the Disk Activity tab showing excessive write rates constantly occurring?

Does the performance of the machine increase when you quit out of particular applications (namely Parallels?)

A defective hard drive could cause slowness, but this may be accompanied by other symptoms (crashing, audible clicking, logging of I/O errors). It may be prudent to run the Apple Hardware Test just to confirm tht the hardware is in good shape.


It's always fun to trace slowdowns. First thing I like to do is regular 6-month maintenance: reset NVRAM and PRAM, repair disk permissions, and reset SMC parameters.

I really like Avast for virus and malware checking on the Mac.

Chrome is notorious for chewing up processing. If you are running 10.9 or later, Safari is a much better choice. For 10.8, it's a good choice.

Parallels, I assume you are running Windows on a VM? Quit Parallels after all the above, and see if that does it. Check with Activity Monitor to see how much RAM is in use, maybe you need more. I think the max on that unit was 16GB.


You may have malware using up resources. Clean it up with Malwarebytes Anti-Malware for Mac (formerly known as AdwareMedic). You download their free app and clean things up. Here is the link:


The program will identify malware and optionally remove it (you should almost certainly remove it).

Malwarebytes Anti-Malware for Mac is entirely free and I have no affiliation with the developers. It is simply the best tool for this job.


There are 3 main possible causes for your issue. When experimenting described slow downs, follow these steps:

1 - RAM: Go to Activity Monitor > Memory. Look at the graphic at the bottom of the window, it is called "memory pressure". It will show you if everything is ok (green), not so much (yellow), or if it is out of memory and it is swapping (red). 8GB should be enough for most users, though.

2 - CPU: Go to Activity Monitor > CPU. Check the graphic at the bottom of your screen. You can easily find if an App is consuming too many resources.

3 - i/o bottleneck. This is harder to troubleshoot, but it is the most likely to happen. If your iMac does not have an SSD / Fusion Drive, your OS X is running on an old HDD that can be producing the slow downs. Sometimes, when mechanical drives are about to fail, they run even slower, causing symptoms like the one you've described. You can test your HDD speed using: Black Magic Speed test:


Reference speeds (read):

  • Mechanical 5400 RPM HDD: ~ 60 MB/s
  • Mechanical 7400 RPM HDD: 90-180 MB/s
  • Low-end SSD: ~220 MB/s
  • Mid-High-end SSD: ~700 MB/s
  • Latest MacBook Pro (2015) SSD (M.2 SSD): ~1300 MB/s

I would encourage you to download etrecheck: http://www.etresoft.com/etrecheck

Then in Etrecheck, you will see

  • /Library/extensions from 3rd parties
  • Startup items from 3rd parties
  • Startup daemons from 3rd parties
  • Internet plugins from 3rd parties
  • Preference panes from 3rd parties

Usually, Some pieces of programs can interfere with the Mac OS. In my case, in 100% of cases, issues are related to 3rd parties (non-Apple)

  • What does this do that is not in Activity Monitor?
    – mmmmmm
    Commented Apr 11, 2016 at 11:32
  • @Mark Not everything can be seen from activity monitor. See edit.Would you see that in activity monitor? Commented Apr 12, 2016 at 11:32
  • Yes if in separate process - plugins would be in the same process likely DLL so not shown. But nothing could show them
    – mmmmmm
    Commented Apr 12, 2016 at 11:46

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