How to speed up VirtualBox on Windows 11 and 10 (fix the slow turtle mode)

These steps are for Oracle VirtualBox 7.x, using the setting names from Oracle’s 7.2 user guide. Power off the VM before changing its settings. If you can’t see a tab or option mentioned here, VirtualBox 7 may be showing its basic view, so switch the Manager to its expert view first.

Step 1: Check for the green turtle

Start the VM and look at the icons at the bottom of its window. Oracle’s manual says a green turtle on the processor icon means a native hypervisor such as Hyper-V is running on the host. In that case VirtualBox can’t use VT-x or AMD-V directly and hands the work to Windows’ hypervisor instead. Oracle describes this mode as experimental and warns that some hosts may see significant performance loss, which is why the VM feels sluggish.

Two other ways to confirm it:

• Press Win + R, type msinfo32 and press Enter. On the System Summary page, Microsoft says you’ll see A hypervisor has been detected. Features required for Hyper-V will not be displayed. near the bottom if a hypervisor is running.
• In VirtualBox, select the VM and open its log (Machine > Show Log). Lines that mention NEM (VirtualBox’s name for running on top of Windows’ hypervisor) point to the same thing.

No turtle, and the processor icon shows a normal chip? Skip to step 3.

Step 2: Turn off the Windows hypervisor (or keep it)

Microsoft explains that only one program at a time can use the CPU’s virtualization hardware, so when Hyper-V or a feature built on it is on, other virtualization apps may fall back to a slower emulated mode. That’s by design, not a bug. Turning it off brings back full speed, but it also turns off WSL 2, Windows Sandbox, Docker Desktop and Memory integrity. If you depend on those, keep them and accept the slower VMs.

To turn it off:

• Open Turn Windows features on or off (search for it from Start). Clear Hyper-V, Virtual Machine Platform, Windows Hypervisor Platform and Windows Sandbox where they’re listed, then select OK. Windows Home has no Hyper-V entry, but the others can still be on.
• Open Windows Security and go to Device security > Core isolation details. Turn Memory integrity off. Microsoft notes it relies on the same hypervisor, and Memory integrity is on by default on many newer PCs.
• Open Command Prompt as administrator and run the command below, then restart.

bcdedit /set hypervisorlaunchtype off

Start the VM again and check the turtle is gone. To undo all of this later, run bcdedit /set hypervisorlaunchtype auto, tick the features again and turn Memory integrity back on. Memory integrity protects Windows against malicious low-level drivers, so turn it back on if you stop using VirtualBox.

If BitLocker is on, have your recovery key ready before you restart, because changes to these security features can sometimes trigger a recovery prompt. Our guide to BitLocker suspended explains how to pause BitLocker for a restart. If VirtualBox refuses to start a VM at all after a Hyper-V change, see Not in a Hypervisor Partition (HVP=0).

Step 3: Make sure VT-x or AMD-V is on

Since version 6.1, VirtualBox requires hardware virtualization and no longer has a switch for it in the VM settings. Open Task Manager, go to Performance > CPU and check that Virtualization says Enabled. If it says Disabled, turn it on in your PC’s UEFI settings: go to Settings > System > Recovery, select Restart now next to Advanced startup, then Troubleshoot > Advanced options > UEFI Firmware Settings. The option is usually called Intel Virtualization Technology (VT-x), or SVM Mode or AMD-V on AMD boards.

Task Manager can say Enabled even while Hyper-V is holding the feature, so this check doesn’t replace step 1.

Step 4: Install or update Guest Additions

Oracle says Guest Additions optimize the guest for better performance and usability, and the newer graphics adapters and 3D support need them. With the VM running, choose Devices > Insert Guest Additions CD Image. In a Windows guest, run VBoxWindowsAdditions.exe from the virtual CD if it doesn’t start on its own, then restart the VM.

In a Linux guest, install the compiler tools and kernel headers first (for example gcc, make and the linux-headers package that matches your kernel), then run this from the CD as root:

sh ./VBoxLinuxAdditions.run

Oracle recommends keeping Guest Additions at the same version as VirtualBox, so reinstall them after each VirtualBox update.

Step 5: Give the VM sensible CPU and memory

In Settings > System > Processor, Oracle advises not giving a VM more CPUs than your PC has physical cores, without counting hyperthreads. Two to four is plenty for most desktop guests, and handing over every core can starve Windows and slow both. Leave Processing Cap at 100%; Oracle notes that lowering it can cause timing problems in the guest.

In System > Motherboard, set Base Memory to what the guest needs, such as 4 GB or more for Windows 11. That memory is taken away from the host while the VM runs, so don’t push it so high that your PC starts paging to disk. If the host CPU itself seems throttled, check why your CPU isn’t running at full speed.

Step 6: Check acceleration and display settings

Under System > Acceleration:

• Paravirtualization Interface: Oracle recommends Hyper-V for Windows guests and KVM for Linux guests. Default normally picks the right one.
• Nested Paging: leave it ticked. Oracle says it gives a significant performance increase on CPUs with Intel EPT or AMD’s equivalent.

Under Display > Screen, use VBoxSVGA for Windows guests and VMSVGA for Linux guests, which are Oracle’s defaults for new VMs. Give the guest enough video memory (raise the slider rather than leaving it at the minimum) and try Enable 3D Acceleration with Guest Additions installed. 3D helps some guests and makes others worse, so test both ways.

Step 7: Speed up the virtual disk

• Keep the VM’s folder on an SSD rather than a hard drive if you can. This is usually the biggest single disk improvement.
• In Storage, attach the disk to a SATA controller rather than IDE. Oracle says SATA is faster and uses less CPU, and that SATA, SCSI and SAS make no real difference.
• Select the disk and tick Solid-state Drive when it sits on an SSD, so the guest treats it as one.
• A dynamically allocated disk is slower while it grows, but Oracle says the penalty becomes negligible once its size settles, so converting to a fixed-size disk is rarely worth it.

Step 8: Tune Windows inside the VM

A Windows guest benefits from the same tweaks as a slow PC. Inside the VM, search for Adjust the appearance and performance of Windows and choose Adjust for best performance, set Settings > System > Power & battery > Power mode to Best performance where available, and turn off startup apps you don’t need in Task Manager’s Startup apps page.

Tweaks that don’t help much

Some older guides suggest switching the chipset to ICH9 or flipping Use Host I/O Cache to make a VM faster. Oracle offers the chipset choice for compatibility, not speed, and describes host I/O caching as a trade-off between safety and memory use rather than a speed boost. Change them only if you have a specific reason. If a VM won’t start at all rather than running slowly, see Failed to open a session for the virtual machine.

Related guides

• Not in a Hypervisor Partition (HVP=0): How to Fix the VirtualBox Error on Windows
• Failed to open a session for the virtual machine: VirtualBox fixes
• BitLocker suspended: what it means and how to resume protection
• CPU not running at full speed in Windows 11/10: how to fix it
• VERR_NEM_NOT_AVAILABLE in VirtualBox: what it means and how to fix it

Official sources

• Oracle VirtualBox 7.2 User Guide: Configuring virtual machines
• Virtualization applications don’t work together with Hyper-V (Microsoft Learn)
• Core isolation and Memory integrity (Microsoft Support)