VMs slows down when moving the window on external monitors.

Discussions related to using VirtualBox on Mac OS X hosts.
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aletullio97
Posts: 1
Joined: 17. Apr 2021, 09:59

VMs slows down when moving the window on external monitors.

Post by aletullio97 »

HOST MACHINE: Macbook Air 2017
GRAPHICS: Intel HD Graphics 6000 1536 MB
MACOS: Big Sur 11.2.3 and later
VIRTUAL BOX Version 6.1.19 and later
Intel HD Graphics 6000:
Type: GPU
Bus: Built-In
VRAM (Dynamic, Max): 1536 MB
Vendor: Intel
Device ID: 0x1626
Revision ID: 0x0009
Metal Family: Supported, Metal GPUFamily macOS 1

1) On my primary display, every VM runs very well. But as soon as I move the window on the secondary display, every VM becomes very slow and unresponsive sometimes.

2) If I unscale the resolution of the VM, let's say I set 800x600 => the VM becomes responsive even on the secondary monitor.

3) If I close the laptop lid and use the second monitor as the primary display, I can use the VM with no problem even at maximum resolution (in my case is 1920x1080x32 @0.0)

4) I tried different software to emulate VMs and the problem seems to be correlated to VBox only.

MOST IMPORTANT
5) If I go to Display settings -> Arrangement and switch the menu bar to the other display, the second display becomes responsive and the primary becomes laggy.

What could be the problem and possible solutions?

I tried to unscale the resolution, use different settings for the VM (different video adapter, memory size, processors...) but with no success. Furthermore, I also tried to monitor the CPU, GPU, memory usage both on the host and the guest machines and nothing appears to be abnormal.
I tried all the possible VirtualBox version macOS Big Sur compatible and even software to use the iPad as a secondary display and the situation is the same.

Please, any help would be very appreciated!
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