Gnome Boxes (rpm), f37 host, sluggish performance with Ubuntu 22.04 LTS guest

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I downloaded and installed Ubuntu 22.04 LTS using the built in dialog in Gnome Boxes.

I allocated 8gb of ram to the VM. By default Gnome Boxes allocates all cpu threads to the VM (in my case 16, using a 12th gen Intel i5).

The performance is very sluggish. Especially moving windows around in the VM’s desktop.

I have another VM in Gnome Boxes with Windows 11 installed which runs very well. I used this tutorial How to run Windows 11 in GNOME Boxes (with UEFI and TPM2 emulation) | Ctrl blog

I don’t know what’s the best practice is for allocated CPU threads. In my mind it makes sense to allocate half of my available threads to leave half for the host. That’s what I’ve done in my Windows 11 VM and it works well. I tried it for the Ubuntu VM and it’s not helping.

What settings, either in the Gnome Boxes GUI or using the qemu underpinnings do I need to modify to get smooth performance?

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I had the exact same issue on my almost identical setup this morning. The ubuntu guest was just unusable. It seems that there is a massive performane hit when using wayland on the guest system. Switching to X11 helped a lot.

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you were absolutely correct. works perfectly now.

For users who don’t know how:

  1. Log out
  2. Click the gear icon on the user login screen
  3. Select xorg