Full Screen 4K Slow - Linux Mint Guest on Windows 10 Host Full Screen 4K

[Trinitron]

Title says it all, I have Linux Mint 19.3 (Cinnamon) guest running on Windows 10 Professional host. Guest additions is installed and updated.

Host system is an 8-core AMD (4.0GHz), 32GB RAM, 8GB Radeon RX580.

The issue I have is I run this VM in full screen at 4K (3840x2160 @ 60Hz). The performance is... average. Running Linux and/or Windows natively on this system is very fast, but the full screen VM performance is slow. It's not unusable, but dragging/moving windows is slow, video is sluggish (YouTube/Zoom), the UI is generally slow.

Is there a driver-set that I can use to improve this? All virtualization settings are enabled on the host bios.

[Trinitron]

Forgot to mention the guest configuration.

Video is set to 128MB
4 cores, 100% processing limit
8GB RAM
Guest HD is hosted on a reasonably fast SSD.


The host is basically idle when I am running this guest, so it's not a resource issue.

I tried installing the AMD driver pack for the Radeon card but it is not detected, something to do with the passthrough?

[mpack]

Well of course running natively is fast, it doesn't have to run on simulated hardware.

Make sure you install the guest additions, make sure the VMSVGA graphics controller is selected, along with 3D acceleration, and give the VM 256MB of graphics RAM.

Edit:  In fact leave it on 128MB. Reduce the allocated core count to 2. Starving the host of CPU does not make the guest faster. 2 cores is best for most VMs running a modern OS. If all else fails cut the display size in half and set the display scale factor (manager|File|Preferences|Display) to 200%. If you want to continue this conversation then a zipped VM log will be required, as I already had to guess some parameters. With the VM fully shut down, right click it in the GUI. Select "Show Log" and save "VBox.log" (no other file) to a zip file. Attach the zip here.

[fth0]

VMSVGA graphics controller is selected, along with 3D acceleration, and give the VM 256MB of graphics RAM.

In the VirtualBox 6.1.8+ Manager, the current limit is 128 MB of Video Memory for VMSVGA with 3D acceleration. Unless you cheat.

[mpack]

Really? I thought the opposite was true, i.e. that it insists on you using 256MB if you enable 3D acceleration.

... but I just tested it and you're quite correct, I don't know how I got the above idea. I guess I don't create many Linux VMs.

[fth0]

I thought the opposite was true, i.e. that it insists on you using 256MB if you enable 3D acceleration.
[...]
I don't know how I got the above idea.

I maybe do.

If you create a Windows guest that supports the WDDM driver model (Windows Vista and newer), and then enable 3D acceleration, the minimum recommended amount of Video Memory (green slider area) is increased to 128 MB. The VirtualBox Manager the shows the famous Invalid settings detected message, but only as a warning.