Fusion running slow on Big Sur using retina display

[daniel8627]

Hello, my VM fusion 12.1.2 is running very slow on Big Sur 11.5.2 when I am not connected to an external monitor. It has been very annoying to type on my 3270 terminal that use to work, while I type the keys got stuck and is only released when I press another key or click with the mouse. I tried to increase/decrease number of memory processors, enable/disable side channel migrations and hypervision applications with no success.

My computer is a MacBook Pro 15-inch, 2,6 GHz 6-Core Intel Core i7, 16 GB 2667 MHz DDR4 and AMD Radeon Pro 5300M 4 GB
Intel UHD Graphics 630 1536 MB.

My VM Fusions works with no issues only while I am connected to my 4k 27" external monitor, even using the retina display as a dedicated display to VM. This is very weird because the monitor should make the computer heavier, I could not find what changes on the VM configuration when my monitor is connected.

Any clue on this?

[ColoradoMarmot]

I wonder if it's because your machine is switching to the integrated GPU when the external monitor isn't connected.  You can change the fusion preferences to 'always use 3d acceleration' to see if that's it.

[AsaA1]

Version 12.1.2 I get a message "Cannot add Graphics acceleration with update". - But there is no update.