When I connect my external monitor, my 2017 MacBook Pro (OS 10.15) will freeze or have severe slowdown for more than a minute. When disconnecting, I often lose windows that I can't recover through any known means except reconnecting to the monitor. Is there a way to reduce the slowdown and have it properly move external windows back to the built-in display?

The monitor is an older SyncMaster using a USB-C -> DVI connector.

1 Answer 1


In the Display settings, under the "Arrangement" tab, I had previously dragged the menubar to the external monitor. This had some benefits, such as causing the Application Switcher to appear on the external monitor, which is the one I was usually looking at. However, moving the menubar back to the built-in monitor eliminated the problems I was having. There is now no slowdown when connecting, and when disconnecting windows reallocate themselves between monitors as expected.

  • Although I posted my own answer, I'd still be interested in seeing one with more context or alternate solutions that let me make the external monitor the primary while it's connected.
    – octern
    Oct 2, 2020 at 20:31

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