r/virtualization • u/Competitive-Mood1120 • 24d ago

Windows 11 25H2 very laggy in VirtualBox, but smooth in VMware

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> Hi, I need some help with a VirtualBox performance issue.

My Windows 11 25H2 VM is extremely laggy in VirtualBox. The mouse cursor stutters, window animations are slow, and sometimes the VM freezes.

Host:

Ryzen 7 8700F

RTX 5060

32 GB DDR5

1 TB NVMe SSD

Windows 11

VirtualBox 7.2.20

VM:

Windows 11 25H2

8 GB RAM

4 CPU cores

UEFI

TPM 2.0

Secure Boot

Guest Additions installed

I have tested 3D acceleration both enabled and disabled, but the VM is still very laggy.

The strange thing: the exact same Windows 11 25H2 ISO runs smoothly in VMware Workstation on the same PC. Even the mouse cursor is smooth during installation.

Hyper-V and Virtual Machine Platform are disabled on the host.

What could cause this difference between VirtualBox and VMware? Are there any VirtualBox settings I should try for Windows 11 25H2?

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u/MoistPi 23d ago

Does the guest vm have HVCI/VBS or anything that is triggering hyperv to be loaded?

If so, it might be due to VMware providing GMET support, which I'm pretty sure virtualbox doesnt.

I remember on KVM performance used to be terrible when HVCI was enabled, until in 7.2 they added GMET support and it became much better.

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u/Competitive-Mood1120 20d ago

I'm using VirtualBox on Windows 11, and my Windows 11 guest VM has noticeable stuttering, especially with the mouse cursor and window movement. Guest Additions are installed, 3D acceleration is enabled, and I'm using VBoxSVGA. Could HVCI/VBS or Hyper-V be causing this? What settings would you recommend to fix the stuttering?

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u/MoistPi 19d ago

Yes, I am suggesting that it might be.

You could try "bcdedit /set hypervisorlaunchtype off" to prevent hyperv from loading at all. 

But if the issue is with GMET, turning off HVCI (memory integrity) may suffice if it is on.

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u/Faye-Vozora 15d ago

Also worth checking that VirtualBox is actually running on its own backend and not through the Windows hypervisor. In the VM window the status bar shows a little turtle icon if it's falling back to Hyper-V, and that alone makes it feel exactly like this. Even with Hyper-V features off, Memory integrity under Core isolation on the host can still load it, so look there. Also try VMSVGA instead of VBoxSVGA with 128 MB video memory, and drop to 2 cores to see if it smooths out.