When VirtualBox is very slow and might show the "green turtle" in the status line.

The problem might be that virtualisation cannot be used by VirtualBox, as the VT-x can only be used by one application. and if used already by Windows or a service thereof, you will not be able to make VirtualBox to use it.


After trying many articles, this one really worked for me:

In essence:

1. Command Prompt (admin mode):

  • bcdedit /set hypervisorlaunchtype off
  • dism /online /disable-feature /featurename:microsoft-hyper-v-all

2. Restart

3. Power Shell (admin mode)

  • get-netadapter|where-object {$_.interfacedescription -like "*hyper-v*"}|Disable-NetAdapter

4. Restart

5. Registry Editor

The following three features are meant to safeguard your PC from malware, so you should only disable them as a last resort if you continue to encounter the same errors in other hypervisors even after disabling Hyper-V.

  • Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\DeviceGuard
    • Create Key: EnableVirtualizationBasedSecurity   DWORD(32-Bit) Value
      • set value to 0 which is default
  • Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa
    • Create Key: LsaCfgFlags  DWORD(32-Bit) Value
      • set value to 0 which is default
  • Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\DeviceGuard\Scenarios\HypervisorEnforcedCodeIntegrity
    • set value of Enabled to 0