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).

I would highly recommend using a Linux OS for virtualization when possible! One of my preferences is Proxmox, which is free to use and supports a wide range of advanced features.

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bcdedit /set hypervisorlaunchtype off

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

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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

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HKLM|SYSTEM|CurrentControlSet|Control|DeviceGuard|EnableVirtualizationBasedSecurity|Enabled and set it to 0.

Core isolation [includes] security features available on your device that use virtualization-based security. This is why they can interfere with VirtualBox and other virtualization tools. Disable them as follow:

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On Win10 hosts, check Settings -> Device Security > Core Isolation Details and make sure all settings in this panel are turned off.

Reboot your system for the new configuration to take affect!