Windows OS Hub
  • Windows
    • Windows 11
    • Windows Server 2022
    • Windows 10
    • Windows Server 2019
    • Windows Server 2016
  • Microsoft
    • Active Directory (AD DS)
    • Group Policies (GPOs)
    • Exchange Server
    • Azure and Microsoft 365
    • Microsoft Office
  • Virtualization
    • VMware
    • Hyper-V
  • PowerShell
  • Linux
  • Home
  • About

Windows OS Hub

  • Windows
    • Windows 11
    • Windows Server 2022
    • Windows 10
    • Windows Server 2019
    • Windows Server 2016
  • Microsoft
    • Active Directory (AD DS)
    • Group Policies (GPOs)
    • Exchange Server
    • Azure and Microsoft 365
    • Microsoft Office
  • Virtualization
    • VMware
    • Hyper-V
  • PowerShell
  • Linux

 Windows OS Hub / Virtualization / VMware / VMware Workstation: Slow VMs Performance on Windows

February 25, 2025

VMware Workstation: Slow VMs Performance on Windows

After installing VMware Workstation on a desktop computer running Windows 11/10, you might experience extremely slow performance and unstable operation of the Windows guest operating system in virtual machines. Interestingly, virtual machines with Windows 10 or 11 guests generally perform well, while VMs running Windows Server 2019 or 2022 tend to be significantly slower during operations. The simple installation of a Windows Server guest in a virtual machine can take several hours to complete.

slow windows server performance on vmware workstation
Poor performance of Windows guests in VMware Workstation can be caused by several factors.

First, examine the vmware.log file stored in the VM directory to analyze the slow performance of a virtual machine in a VMware environment.

vmware.log - vmx Monitor Mode: ULM

Note the following information entries in the VM log:

2025-02-14T12:03:45.874Z In(05) vmx MsgHint: msg.loader.mitigations.wsAndFusion
2025-02-14T12:03:45.874Z In(05))+ vmx You are running this virtual machine with side channel mitigations enabled. Side channel mitigations provide enhanced security but also lower performance.
2025-02-14T12:03:45.877Z In(05)+ vmx
2025-02-14T12:03:45.877Z In(05) vmx To disable mitigations, change the side channel mitigations setting in the advanced panel of the virtual machine settings. Refer to VMware KB article 79832 at https://kb.vmware.com/s/article/79832 for more details.

This indicates that the VM has side-channel attack protection enabled (typical vulnerabilities of this class are Spectre and Meltdown), which restricts third-party processes (including virtual machines) from accessing protected kernel (host) memory. Side channel mitigation is enabled by default for all VMs on Windows hosts with Virtualization Based Security (VBS) enabled. This protection can be disabled in the VMware Workstation GUI (VM Properties -> Options -> Advanced -> enable the Disable side channel mitigations for Hyper-V enabled hosts option) or in the VMX configuration file of the VM by adding the parameter:

ulm.disableMitigations="TRUE"

Disable side channel mitigations for Hyper-V enabled hosts

ulm.disableMitigations in VMware VM

If this does not resolve the poor VM performance issue, look for another line in the vmware.log:

2025-02-14T12:03:45.877Z In(05) vmx Monitor Mode: ULM

This indicates that VMware Workstation is running in User Level Mode (ULM). ULM mode causes VMs on the hypervisor to run in user mode instead of kernel mode. In this mode of running a VM on VMware Workstation, the guest OS performance will be severely degraded, resulting in significant slowdowns during almost any action. If the Windows host has Hyper-V hypervisor capabilities installed, VMware Workstation will automatically run the virtual machine in ULM mode.

In this case, the only way to solve the problem is to disable the Hyper-V virtualization features in the host OS. This allows the Virtual Machine Monitor (VMM) component to directly access the virtualization instruction set of the physical CPU, bypassing the additional Windows Hypervisor Platform API layer.

Verify that the host is allowed to run Hyper-V capabilities:

BCDEdit /enum| select-string "hypervisorlaunchtype"

The hypervisorlaunchtype Auto in the output means that the Windows boot loader can run Hyper-V virtualization platform components.

Disable the Hyper-V hypervisor from launching at boot time:

bcdedit /set hypervisorlaunchtype off

bcdedit disable hypervisorlaunchtype

Reboot the computer and check to see if the performance of your Windows Server virtual machine in VMware has improved.

Note that this will disable the ability to use several additional features on the host that depend on Virtual Machine Platform components, including:

  • Hyper-V virtual machines
  • WSL2 (Windows Subsystem for Linux 2)
  • Windows Sandbox
  • Credential Guard and Device Guard
WSL2 is not supported with your current machine configuration.
Please enable the "Virtual Machine Platform" optional component and ensure virtualization is enabled in the BIOS.
Enable "Virtual Machine Platform" by running: wsl.exe --install --no-distribution
Error code: Wsl/Service/CreateInstance/CreateVm/HCS/HCS_E_HYPERV_NOT_INSTALLED

WSL2 is not supported with your current machine configuration. Please enable the "Virtual Machine Platform" optional component and ensure virtualization is enabled in the BIOS.

To allow the execution of Hyper-V components, use the command:

bcdedit /set hypervisorlaunchtype auto

Disabling core isolation in Windows settings can also improve VM performance in some cases. (Windows Security -> Device Security -> Core Isolation details -> Memory Integrity). Of course, this means that Windows becomes less protected, potentially exposing the system to security vulnerabilities.

Disable Memory Integrity on Windows 11

Most modern CPUs support Power Throttling mode. The idea is that the operating system can limit CPU usage for background processes to save power and extend battery life. Power Throttling mode might cause slow performance of VMware processes on computers with 12th, 13th, and 14th generation Intel CPUs on computers running Windows 11 24H2.

To prevent Windows from using the power throttling mechanism to limit CPU usage for the main VMware Workstation process, run the following command

powercfg /powerthrottling disable /path “C:\Program Files (x86)\VMware\VMware Workstation\x64\vmware-vmx.exe”

Verify that the vmware-vmx.exe process is added to the exclusion list.

powercfg /powerthrottling list

Boost VMware Workstation performance by disabling powerthrottling

Windows will not attempt to manage power settings for the processes you specify. In this case, VMware Workstation workloads will always run in maximum performance mode.

0 comment
0
Facebook Twitter Google + Pinterest
Questions and AnswersVMwareWindows 11Windows Server 2022
previous post
How to Hide (Block) a Specific Windows Update
next post
How to Write Logs to the Windows Event Viewer from PowerShell/CMD

Related Reading

How to Fix ‘An Operating System Wasn’t Found’...

August 24, 2023

Adding Drivers into VMWare ESXi Installation Image

March 13, 2024

How to Install Free VMware Hypervisor (ESXi)

March 17, 2024

Adding ESXi Host to VMware vCenter Server (vCSA)

March 12, 2024

Reset Root Password in VMware ESXi

October 6, 2023

How to Access VMFS Datastore from Linux, Windows,...

March 11, 2024

Using iPerf to Test Network Speed and Bandwidth

March 12, 2024

Unmounting an NFS Datastore from VMware ESXi

March 12, 2024

Leave a Comment Cancel Reply

join us telegram channel https://t.me/woshub
Join WindowsHub Telegram channel to get the latest updates!

Recent Posts

  • Configuring Windows Protected Print Mode (WPP)

    May 19, 2025
  • Map a Network Drive over SSH (SSHFS) in Windows

    May 13, 2025
  • Configure NTP Time Source for Active Directory Domain

    May 6, 2025
  • Cannot Install Network Adapter Drivers on Windows Server

    April 29, 2025
  • Change BIOS from Legacy to UEFI without Reinstalling Windows

    April 21, 2025
  • How to Prefer IPv4 over IPv6 in Windows Networks

    April 9, 2025
  • Load Drivers from WinPE or Recovery CMD

    March 26, 2025
  • How to Block Common (Weak) Passwords in Active Directory

    March 25, 2025
  • Fix: The referenced assembly could not be found error (0x80073701) on Windows

    March 17, 2025
  • Exclude a Specific User or Computer from Group Policy

    March 12, 2025

Follow us

  • Facebook
  • Twitter
  • Telegram
Popular Posts
  • Fix: Windows Update Tab (Button) is Missing from Settings
  • Fix: Your IT Administrator Has Limited Access to Virus & Threat Protection
  • Permanently Disable Driver Signature Enforcement on Windows 11
  • Fix: Multiple Connections to a Server or Shared Resources by the Same User
  • How to Add or Reinstall the Microsoft PDF Printer on Windows
  • Remote Desktop fix: The number of connections to this computer is limited
  • Windows: How to Turn Off Monitor with Command Line
Footer Logo

@2014 - 2024 - Windows OS Hub. All about operating systems for sysadmins


Back To Top