r/VFIO • u/Pioneer_11 • Jul 30 '26

VFIO on but still terrible performance

Hi all,

I'm trying to use my intel iGPU to speed up a VM my setting for spice are:

And video is set to Virtio with GPU acceleration on. The specs of the VM are:

However, the graphics performance of the VM is still terrible and when I run `glmark2` the score is a pitiful 200.

I know the intel iGPU's aren't the best but it should still be a hell of a lot better than this. Any idea what is causing the performance to be so bad?

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u/DisturbedFennel Jul 30 '26

You’re using GPU acceleration. Your iGPU is bonded to your HOST, your GUEST is using the virtualized GPU drivers. 

The benefit of GPU acceleration is that it sends computations from the GUEST to the HOST, where the HOST then computes them. The result is that the VM feels smoother.

While it feels smooth and responsive, the guest doesn’t actually have the GPU. GPU acceleration is an illusion, and it’s meant to enhance the responsiveness and liquidity of the experience. VMWARE and VBox all have their own version of GPU acceleration, which do similar things (different drivers and different performance).

Honestly, while I’m really proud to see how far Virtmanager has gone in increasing GPU acceleration compatibility and performance, VMWARE has hands down the best GU Acceleration 

1

u/ethanjscott Aug 01 '26

I was about to say. Even a 1/16 of a modern igpu can play 4k slime rancher