VirtualBox is slow on Windows 11 when Hyper-V or virtualization-based security is using the CPU’s virtualization feature (VT-x or AMD-V), so VirtualBox falls back to a slower mode and shows a green turtle icon. Turn off Hyper-V, Virtual Machine Platform, Windows Hypervisor Platform and Memory integrity, restart, and the normal “V” icon returns.
VirtualBox slow on Windows 11 is what I faced when I migrated my home computer to new hardware. The VMs started working too slow, so slow that they were completely unusable. Even though the new hardware was more powerful than the old PC, it was a real shock when the virtual machines suddenly acted like this.
Technically the existing virtual machines should work well on new hardware. I had no doubts about the processor or RAM support since I installed the latest version of Oracle VirtualBox.
I had every doubt about the Windows 11 operating system only. Since it was a fresh installation without much modification, I was unsure where to start the troubleshooting.
In this guide, let me show the steps to fix painfully slow VMs on VirtualBox with a Windows 11 host. You can use the same methods on Windows 10 computers also.
I wrote this when Windows 11 was new and VirtualBox VMs were really slow on it. I have not retested these steps on the latest Windows 11 build or VirtualBox 7.x, but the cause has not changed. Microsoft still documents that third-party virtualization apps such as VirtualBox can’t run alongside Hyper-V, Memory integrity or Credential Guard.
Why Is VirtualBox So Slow on Windows 11?
VirtualBox is slow because the Windows hypervisor (Hyper-V and the features built on it) holds the VT-x virtualization feature of your CPU, and VirtualBox can’t use it at the same time. VT-x is what VirtualBox needs to run the VMs at full speed.
Even if you never installed Hyper-V, or already removed it from the Control Panel, you may still see extremely slow virtual machines. Windows security features such as Memory integrity use the same hypervisor. Microsoft turns Memory integrity on by default for clean installs of Windows 11 on compatible hardware (not for upgrades). That is likely why a brand new PC with a fresh installation, like mine, can have this problem without Hyper-V ever being enabled.
How to Identify that the VM is Struggling on a Windows 11 Host?
- The VM boot is too slow. Sometimes you will not get the desktop screen even after 10 minutes.
- You will notice a green turtle icon in the status bar of the virtual machine console. This indicates that VirtualBox is running in a slower mode.
Hyper-V and VirtualBox can’t use the VT-x (Virtualization technology) at the same time on a computer. We discussed a similar problem earlier here.
How to Fix VirtualBox Slow on Windows 11/10 Host
1) Uninstall the Hyper-V Features
If you installed Hyper-V, Windows Sandbox, Docker or anything related to Hyper-V recently, you need to remove them.
These features and VirtualBox can’t work together well on a computer. Microsoft services like Hyper-V access the VT-x technology first while the host OS boots up; hence, VirtualBox can’t access it later.
Windows 11 and Windows 10 have slightly different names for these features. Make sure to find the correct one and remove them.
Go to Control Panel > Programs and Features. Click on the ‘Turn Windows features on or off’ option to remove Hyper-V and the related features.
Make sure to untick Hyper-V, Virtual Machine Platform, Windows Hypervisor Platform and Windows Sandbox. If you use WSL 2 or Docker Desktop, note that they depend on some of these features, so they will stop working too.
Press OK to remove the features, then restart the computer.
Once the computer is rebooted, power on the virtual machines in VirtualBox and see whether they work at the normal speed. The green turtle icon should not appear in the VM console.
If this doesn’t help, go to the next step.
In my example, it was a fresh installation of Windows 11 on brand new hardware. I did not enable Hyper-V or any extra services. So, in the Control Panel, I did not see these options selected, yet the VMs worked very slowly in VirtualBox.
2) Clean Removal of Hyper-V Using Command Prompt
Several feedbacks are available online to perform a clean removal of Hyper-V from the command prompt.
Open the command prompt as administrator and run the following command to stop the hypervisor from starting with Windows.
bcdedit /set hypervisorlaunchtype offThen use the DISM command to disable the Hyper-V hypervisor feature. This is the feature name Microsoft documents for it.
DISM /Online /Disable-Feature /FeatureName:Microsoft-Hyper-V-HypervisorShut down the computer after the above commands and wait for 20 seconds. Then switch on the computer to see the difference. If you want Hyper-V back later, run bcdedit /set hypervisorlaunchtype auto and enable the feature again.
Technically, this step did not help me either. The commands I ran back then returned a successful message at the end. Still, the virtual machines in VirtualBox worked exceptionally slow.
To verify whether this was affecting only the existing virtual machines, I created a new virtual machine and started installing Windows 10 on it. The process was painfully slow, and I could not continue further, because the new VM also started with the green turtle icon.
If none of the above steps helps you, the next option is Core isolation in Windows Security. Also, the Device Guard and Credential Guard options.
3) Disable Memory Integrity (Core Isolation) in Windows Security
Microsoft’s note says when you disable Hyper-V, you should also disable the features that depend on it, Memory integrity and Credential Guard. Start with Memory integrity.
It is one of the virtualization-based security options that use the hypervisor and the VT-x of the computer. Even though we removed the Hyper-V feature completely from the PC, the VirtualBox VMs can work very slowly if Memory integrity is still active.
- Open the Windows Security app (search for ‘Windows Security’ in the Start menu).
- Select Device security, then Core isolation details.
- Switch off the Memory integrity option. This requires a restart of the computer.
Windows 11 will show a warning in Windows Security after this, since the protection is off. That is expected. Memory integrity protects the Windows kernel from malicious code, so on your daily PC, think about whether you need VirtualBox speed more than that protection. On a test machine it is an easy call. If the drive is encrypted with BitLocker, keep the recovery key handy before you change these settings, just as a precaution.
My VirtualBox virtual machines started working well by disabling this option and rebooting the computer. Also, the green turtle symbol disappeared and the ‘V’ symbol returned like normal. That is a clear sign that the virtual machines are using the VT-x feature of the computer hardware properly.
4) Disable Device Guard and Credential Guard
Since disabling Memory integrity solved my issue, I did not need to try this step. I believe it may not apply to your Windows 11 PC either.
Device Guard and Credential Guard are slightly more complicated options. They can be enabled by Group Policy, Intune, the registry, or the memory integrity settings. If none of these tools turned them on for your computer, they will not create the slow VM issue in VirtualBox. On a work or domain-joined PC, they are often set by policy, so check with your IT team before you change them.
If you still face the issue and need to disable these options, check out the below guides.
How to Check that the Hypervisor is Really Off
The turtle icon is the quickest sign, but you can also check Windows itself after the restart.
- Press the Windows key, type msinfo32 and open System Information.
- On the System Summary page, look at the bottom for the Virtualization-based security lines. They should not say ‘Running’.
- If you see the line “A hypervisor has been detected. Features required for Hyper-V will not be displayed”, a hypervisor is still running.
In an administrator PowerShell window, this command gives a quick answer. False means no hypervisor is loaded.
Get-CimInstance Win32_ComputerSystem | Select-Object HypervisorPresentTo see which security features are running, use the command below. In SecurityServicesRunning, the value 1 is Credential Guard and 2 is Memory integrity.
Get-CimInstance -ClassName Win32_DeviceGuard -Namespace root\Microsoft\Windows\DeviceGuardStill Slow? Other Things that Keep the Hypervisor On
If the turtle is still there after all the steps, look for these:
- WSL 2 and Docker Desktop. They use the Virtual Machine Platform, so the hypervisor stays loaded as long as they are installed and enabled. Some users report that the hypervisor stays on even after the features are unticked on upgraded systems or on PCs that used WSL 2 or Docker earlier.
- Windows Hypervisor Platform and Windows Sandbox. Check they are unticked in the Windows features list, as in step 1.
- Virtualization in BIOS. If VT-x or AMD-V is off in the BIOS, VMs will not start properly at all. Here is how to enable virtualization in BIOS.
If you need Docker or WSL 2 on the same PC, you have two choices. Accept VirtualBox in the slower mode, or move the VMs to Hyper-V. The VDI to VHD/VHDX conversion guide shows how to move them. The VirtualBox 7.2 change log lists better CPU feature reporting when it runs on the Windows Hyper-V engine, but I have not measured how much that helps.
FAQ
What does the green turtle in VirtualBox mean?
It means VirtualBox is running in a slower mode because Hyper-V or Windows virtualization-based security is using the hardware virtualization feature. When it is fixed, the normal ‘V’ symbol comes back.
Can VirtualBox and Hyper-V run together on Windows 11?
Yes, but VirtualBox may run in the slower mode. Microsoft says third-party virtualization apps can’t share the hardware virtualization feature with Hyper-V, Memory integrity or Credential Guard. For full speed, turn them off.
How to make VirtualBox run faster on Windows 11?
First check the status bar. If you see the green turtle, follow the steps above. If you see the normal ‘V’ symbol, this problem is not your issue. Then check that virtualization is enabled in the BIOS and that the VM has enough memory and CPU cores.
Why is my virtual machine running so slowly after a Windows 11 upgrade?
If VirtualBox is running slow on Windows 11 right after an upgrade, check the same things. Microsoft turns Memory integrity on by default only for clean installs, not upgrades, so the usual suspects after an upgrade are the Hyper-V features, WSL 2, Docker Desktop or a policy that turned on virtualization-based security. Follow the steps above and look for the green turtle first.
For me, turning off Memory integrity and restarting was what finally worked. If a different step fixed it on your PC, share it in the comments.
