My Macbook Pro, running on High Sierra, gets extremely slow whenever I'm using video chat. It happens both when using Skype and Zoom. Under normal conditions it's fast and smooth, but as soon as I use video chat things go south and the computer becomes unresponsive and sluggish.

I think what may be related to it is that I'm using both an external monitor and an iMac (via thunderbolt). But it's strange to me that it all functions correctly when I'm not on video chat, even when I have the laptop screen open as well.

Any ideas what could cause this?

The specs of my computer are:

  • Macbook Pro (retina, mid 2012) running on OSX 10.13.5
  • 2.3 GHz i7
  • 16GB RAM
  • 256GB SSD
  • GeForce GT 650M
  • does it lag anytime the camera is being used or just during a video chat?
    – malton33
    Jul 11, 2018 at 0:29
  • 2
    Does the lag exist when the external monitor is disconnected?
    – IconDaemon
    Jul 11, 2018 at 14:29
  • @startTerminal It's mostly during video chats. So when I just have Photo Booth open for example it doesn't happen.
    – Ruben
    Jul 11, 2018 at 18:21
  • 1
    @IconDaemon I just tried that out during a video call and it actually made a big difference. So when I only have the laptop screen open + the iMac as an external monitor and the other monitor disconnected from the HDMI port it does work smoothly! Thanks for the suggestion and if you want, put it up as an answer and I'll accept it.
    – Ruben
    Jul 11, 2018 at 18:23
  • 2
    it's most likely the fact that the video chat and the external monitor are putting such a strain on the little GPU that it can't handle both of them
    – malton33
    Jul 11, 2018 at 20:13

1 Answer 1


It is more than likely that the increased demand on the GPU (processing and RAM) by supporting both the external monitor and the MacBook Pro screen while using Skype or Zoom causes the MacBook Pro to lag. Since you mention that the GPU is rather old and has only 1 GB of RAM, this is probably the problem.

Skype may give you the ability to lower the video quality and resolution, putting less demand on the GPU. If you can still Skype with the external monitor disconnected, this may be the best solution.

  • I have 32 Gb of Ram on intel i9 with dedicated Radeon Pro for video. But skype uses 100% or more of CPU when having video calls. Everything is slower, even when typing. Disconnecting the second monitor definitively helped for some reason. May 6 at 0:40

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