Why is Windows 11 making VMware VMs ‘suffer’?
Just upgraded to Windows 11 on my ThinkPad i7-12700H and eagerly opened VMware to run my Lab, only to get a “slap in the face”: “Virtualization technology is not enabled”. Even though I had enabled VT-x in the BIOS beforehand, the VM still threw errors or crawled like a snail. As someone managing an 8-host ESXi cluster, having my personal Lab environment fail is unacceptable.
In reality, Windows 11 enables Virtualization-based Security (VBS) by default. This creates a hidden Hyper-V layer for security. This layer seizes control of the hardware, pushing VMware to the sidelines and preventing it from directly accessing the CPU’s VT-x instructions. The result is a performance drop of up to 40% or VMs failing to start altogether.
To fix this, simply hitting ‘Enable’ in the BIOS isn’t enough. You need a combo to completely clear all traces of Hyper-V.
A 4-step process to fix the error for good
I’ve applied this process to dozens of machines, from Dell Latitudes to dedicated workstations, and they’ve been running stably for the past 6 months.
Step 1: Check BIOS/UEFI – Don’t forget the “Cold Boot”
This is the foundation. Ensure **Intel Virtualization Technology** or **SVM Mode** (AMD) is set to **Enabled**.
Pro tip: On Dell Precision laptops, this is under Virtualization Support. After making changes, shut down the computer completely before turning it back on. Never select Restart. Some motherboards only reload the virtualization microcode during a full power cycle.
Step 2: Clean up Windows Features
Windows 11 has many services that rely on Hyper-V. Go to Turn Windows features on or off and uncheck the following:
- Hyper-V (all sub-folders).
- Virtual Machine Platform.
- Windows Hypervisor Platform.
- Windows Sandbox.
Don’t restart just yet. Proceed to Step 3 to save time.
Step 3: Disable the Hypervisor via CMD
Even if disabled in the GUI, Hyper-V can still activate itself at boot. This is the “final blow”. Open Command Prompt as Administrator and run:
bcdedit /set hypervisorlaunchtype offThis command forces Windows not to load its own hypervisor layer, giving full priority to VMware for CPU access.
Step 4: Disable Core Isolation (Memory Integrity)
The Memory Integrity feature is the silent culprit behind most conflicts on Windows 11. It uses VBS to protect processes but is highly “allergic” to third-party VMs.
- Open Windows Security > Device Security.
- Go to Core isolation details.
- Toggle Memory integrity to Off.
Now, restart your computer for the changes to take effect.
Configuring VMware for maximum speed
Now that the OS is clear of Hyper-V, it’s time to optimize the software. In the VM Settings > Processors section, check:
- Virtualize Intel VT-x/EPT or AMD-V/RVI: Required if you plan to install Docker or nested ESXi in VMware.
- Virtualize CPU performance counters: Helps performance measurement tools run accurately.
If the VM still reports Side-channel security vulnerabilities, add this line to your .vmx file:
ulm.disableMitigations = "TRUE"This tip allows the VM to skip security patches that slow down the CPU (like Spectre), significantly improving response times.
How to check if you’ve reached the “finish line”?
Don’t just assume it’s working because the VM starts. Check these two signs:
First, open Task Manager (Ctrl+Shift+Esc) and go to the Performance tab. Virtualization must be Enabled. If it’s Disabled, antivirus software (like Avast) might be hogging VT-x.
Second, go to the folder containing your VM and open the vmware.log file. Search for the keyword “monitor mode”. If you see the line:
Monitor Mode: CPL0Congratulations, you’ve succeeded! CPL0 mode means VMware is running directly on the hardware. If you still see ULM (User Level Monitor), it means the machine is still running through Windows APIs, and performance will be poor.
This fix has made my Lab environment smooth, with no more mouse lag when opening heavy apps. Good luck with your configuration!
