Make sure that is OFF. Start windows power shell (as ADMIN), and type
bcdedit /set hypervisorlaunchtype off
Now reboot windows. Must reboot.
Now can start virtual box. Check the icon on the lower right corner of the vbox linux terminal. If no Turtle sign shows up but V sign, then good, it means Vbox is in fast mode.
To start SWL again, do
bcdedit /set hypervisorlaunchtype auto
From powershell as ADMIN and reboot windows again.