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Extremely slow performance after the upgrade to Yosemite on iMac12 Mid 2011

  • Parallels Desktop for Mac Home Edition


My virtual machine is extremely slow after I upgraded my Mac to the OS X 10.10 Yosemite.

I have iMac12,1 or iMac12,2 (Mid 2011).

When I move my mouse back and forth over the virtual machine's screen the performance returns to normal until I stop moving the mouse.


Most probably the issue is caused by the interrupt storm in driver. Please follow this article to confirm that: KB117114.


Please set the boot argument on the Mac to workaround the issue:

  1. Run Terminal (/Finder/Applications/Utilities/ and execute the command:

    sudo nvram boot-args="debug=0x10"

    You will need to type Mac Administrator password and hit Enter (return) (you will not see the symbols you type. It's OK.)

    This command enables the debugging mode. It means that if Mac crashes it will attempt to collect the kernel dump. It will not affect the Mac performance.

  2. Reboot your Mac

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