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Table of Contents
VirtualBox Windows 10 / 11 performance issues
Intro
It's possible to have severe performance issues using VirtualBox on Windows. This is usually caused by Microsoft forcing their own Hyper-v hypervisor to startup with Windows in the background. This blocks direct access to intel's and AMD's virtualization on the CPU's. VirtualBox is therefore forced to fallback to Hyper-V, running all VM's as nested VM's on top of it.
This issue is indicated with a green turtle icon in the bottom taskbar of a started VirtualBox VM (as seen in the example image). 
Solution 1:
Use a host OS that's not architecturally defective at it's core, e.g something based on a Linux distro of choice!
Solution 2:
1) Disable the Microsoft Hypervisor:
- Type:
bcdedit /set hypervisorlaunchtype off
2) Disable Device guard:
On some Windows hosts with an EFI BIOS, DeviceGuard or CredentialGuard may be active by default, and interferes with OS level virtualization apps in the same way that Hyper-v does. These features also need to be disabled.
On Pro versions of Windows you can do this using gpedit.msc
- Type:
set Local Computer Policy > Computer Configuration > Administrative Templates > System > Device Guard > Turn on Virtualization Based Security to Disabled.
CredentialGuard is a subset of DeviceGuard, so disabling the former should be enough. If you cannot use gpedit for some reason then the equivalent registry hack is to find the key
- Type:
HKLM|SYSTEM|CurrentControlSet|Control|DeviceGuard|EnableVirtualizationBasedSecurity|Enabled and set it to 0.