Troubleshooting Fusion virtual machine performance issues
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Troubleshooting Fusion virtual machine performance issues

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Article ID: 328081

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Updated On: 04-09-2025

Products

VMware Desktop Hypervisor

Issue/Introduction

Symptoms:
You experience any of these symptoms:

  • Excessive time to resume from suspend state
  • Excessive time to launch Windows applications
  • The Mac host becomes unresponsive
  • Your mouse cursor frequently looks like a spinning beach ball
  • The guest operating system boots slowly
  • Applications running in virtual machines perform poorly
  • Applications running in virtual machines take a long time to launch
  • Applications running in virtual machines frequently become unresponsive
  • Multi-user services have long transaction times or handle less simultaneous users than expected



Resolution

Fusion virtual machine performance is impacted by a number of factors. Some of these can be managed with Fusion for the guest operating system (the virtual machine), while others are managed by the host operating system (Mac OS X).

To resolve performance issues, some settings must be configured within the virtual machine itself. These settings are specific to the operating system, so you should consult your operating system documentation for information.

Each of these steps provides an instruction and a link to a document for validating the step and taking corrective action as necessary. The steps are ordered in the most appropriate sequence to isolate the issue and to identify the proper resolution. Work through each troubleshooting step in order and do not skip a step.

If you perform a corrective action in any of these steps, check your performance again to see if it has improved.

To troubleshoot performance:

  1. Determine if the reduced performance is expected. When a workload is virtualized, it is common to have some performance reduction due to virtualization overhead. Troubleshoot the performance problem only if:
     
    • The virtual machine was previously working at acceptable performance levels.
    • The virtual machine performs significantly slower than a similar setup on a physical computer.
    • You want to optimize your virtual machines for the best performance possible.
       
  2. Verify that you are running the most recent version of Fusion. For more information, see Downloading and installing VMware Fusion (2014097).
     
  3. Ensure that VMware Tools is installed in the virtual machine and running the correct version. The version listed in the toolbox application must match the version of the product hosting the virtual machine. To access the toolbox, double-click the VMware icon in the notification area on the Windows task bar or run vmware-toolbox in Linux. When the virtual machine boots up, Fusion displays a message if the versions do not match.

    For more information on VMware Tools, see Overview of VMware Tools for VMware Fusion (1022048).
     
  4. The processes running in Windows operating system might utilize high CPU and this results in poor performance of the virtual machine. Keeping unnecessary processes in startup list, increases the time needed to load windows and affects the overall performance. To disable non essential startup items in Windows, use the msconfig utility in Windows. For more information, see Using the Windows System Configuration utility (1004010)
     
  5. Review the virtual machine's virtual hardware settings and verify if you have provided enough CPU and memory resources to the virtual machine. Use the average hardware requirements typically used in a physical machine for that operating system as a guide. Adjustments to the settings are required to factor in the application load; higher for larger loads, such as databases or multi-user services, and lower for less intense usage, such as casual single-user applications like email or web browsers.

    Specific recommendations:
     
    • Processors – If you have a dual-core CPU and you assign two CPU cores to the virtual machine, the physical computer may not get enough resources and compete with the guest for CPU time. The host operating system needs one CPU core for itself. (Fusion does not differentiate between CPUs and CPU cores; it considers two dual-core CPUs to be the same as one quad-core CPU. In either case, there will be four cores available to be assigned, whereas only two of them should be assigned.)
    • RAM – Mac OS runs best with at least 2 GB of RAM dedicated to itself. On a system with 4 GB of RAM, it is best to allocate no more than 2 GB for a guest OS. If you allocate more than that, the host may not get enough RAM.
       
    For more information, see Investigating virtual machine resources in VMware Fusion (1022213).
     
  6. Look for overly-active, disk-using Windows services. Applications like Windows indexing services and antivirus programs double or triple the number of read operations to be performed by the hard disk. The hard disk is the slowest component in modern computers, so this doubled or tripled waiting time can make it seem like the virtual machine is not responding. This leads to a spinning beachball cursor and both the Mac and the Windows virtual machine become unresponsive while Windows waits for the read operations to finish and the Mac waits for Windows to finish waiting.

    Note: To identify the applications that may be overly-active, see Investigating operating system CPU usage (1004016). Any services that have a high CPU usage might cause this issue and, if possible, should be disabled. (A web search for the name of the process usually helps you to identify the application to which it belongs. You can stop that application from automatically starting up or you can uninstall it.)
     
  7. If there is a process using an excessive amount of the guest CPU, follow the steps in Troubleshooting a Fusion virtual machine that uses 100% of the guest CPU (1027674).
     
  8. Look for a Mac application that is consuming a high amount of CPU cycles. Performance issues can also be caused by another Mac application that has problems and is running in the background.
     
    1. The Mac's Activity Monitor (go to [Macintosh HD] > Applications > Utilities > Activity Monitor) can be used to view all running applications and processes on the Mac. If a process other than vmware-vmx is using a high amount of CPU, it may cause the virtual machine to perform slowly because the Mac is unable to allocate enough CPU resources to the virtual machine. If another program is using a high amount of CPU, it is either in the middle of doing something or is having a problem and should be investigated.
       
    2. Check the Console (go to [Macintosh HD] > Applications > Utilities > Console) and view the system.log file to see if there are any repeating errors which fill the log. Though it is difficult to say if the error is causing the performance issue, the exact error would give you more information. You may need to disable or uninstall/reinstall the offending application.
       
  9. If there is an application or process using an excessive amount of the Mac's CPU, follow the steps in Troubleshooting a Fusion virtual machine that uses 100% of the Mac's CPU (1027723).
     
  10. Consider hard disk issues as a potential cause of the problem. For more information, see Troubleshooting Fusion virtual machine performance for disk issues (1022625).
     
  11. If you have upgraded from Fusion 2.x, create a new virtual machine. Fusion 3 has several performance enhancements, some of which can only be taken advantage of with a new virtual disk. To isolate a performance problem, create a new virtual machine with your Windows installation media and use Easy Install to see if it performs the same way. Moving from one virtual machine to another can be made seamless with the use of Shared Folders and Mirrored Folders. If the new virtual machine runs fine, the issue is related to the other virtual machine, Windows, or the virtual disk.

    For more information, see:
     
  12. Verify that the Mac operating system is working properly and is healthy. For more information, see Verifying the health of an operating system (1003956).

If the issue continues to exist after trying the steps in this article:



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