Improve virtual machine performance on Mac

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Symptoms

Cause

There might be multiple reasons causing the low performance, such as:

The Basics

Virtual machine performance is directly related to a computer's hardware resources. It is also very important to allocate even shares of hardware resources between the host operating system (macOS) and guest (VM) according to the recommended system requirements of both systems.


Note: starting with version 14, Parallels Desktop for Mac brings a new feature: CPU Usage Monitor. Look at the VM window tray and CPU Usage Monitor will light up in red when CPU usage in Windows is above 70%. Click on CPU Usage monitor to see what processes in Windows use the computer's CPU. Clicking on a process name will open Windows Task Manager showing selected process:


The computer's performance mostly depends on several hardware components: CPU, RAM, and hard disk. While CPU cannot be replaced at hand, most of Mac computers enabled for RAM and hard disk upgrade.

Upgrading Your Mac with a Solid State Drive

If your Mac uses a hard disk drive (HDD), it is highly recommended to replace the drive with a solid-state one (SSD). This is the #1 recommendation for all Mac users which gives the significant performance boost to Mac at 2-3 times. Contact your local Apple Authorised Service Provider to get assistance with the disk replacement.

TIP: you can check your Mac's drive type at the 'System Information' report (click  > About this Mac > System Report... > Hardware > SATA/SATA Express)

Upgrading Your Mac with Better Memory Modules (RAM)

If you notice in Activity Monitor that your memory pressure is up to the maximum, it's time to check if your Mac allows you to do RAM replacement with higher modules capacity.

Visit these articles for more details:


Checking Software Settings

macOS

  1. Make sure that you have ample free disk space on your startup disk. Visit this article for more details: KB 123553.
  2. Use Activity Monitor to check what unwanted applications consume a high percentage of system resources (CPU and Memory).
  3. Make sure Time Machine backup is not taking place while you’re running the virtual machine. The backup process may slow down overall system performance.

Parallels Desktop Preferences

  1. Make sure you're using the latest build for your Parallels Desktop version:

    • On the macOS menu bar click the Parallels Desktop icon > Check for Updates... Download and install the updates if available.
  2. Store your virtual machine within Mac HD (internal storage). Running a VM from an external USB disk or NAS may significantly lower VM performance.
  3. Be careful running several virtual machines at once - each VM consumes a considerable amount of resources and may slow down overall computer performance.
  4. Try disabling antivirus on the Mac side. Alternatively, you may add adding Parallels Desktop/virtual machine location to a white list that antivirus maintains of known good software.

Virtual Machine Configuration


Note: starting with Parallels Desktop 17, we advise using the Automatic Resource Manager feature. Parallels Desktop 17 evaluates your Mac hardware before starting a virtual machine to allocate as many resources as needed to provide a better out-of-the-box experience for our users. When deploying a virtual machine to various different Mac hardware, this new feature helps to ensure that your users will get the best possible experience with Windows on their Macs.


Make sure you have set this option by opening the virtual machine configuration > Hardware > CPU & Memory > select Automatic (Recommended).

 

If you want to manually adjust the number of CPUs and the amount of memory assigned to the virtual machine, perform the steps below:

 

If you use Parallels Desktop 16 or earlier Parallels Desktop versions, shut down your VM (Actions > Shut down) > open its configuration > switch to Hardware tab > CPU & Memory > make sure that the number of processors (CPUs) and the amount of memory do not exceed the recommended values. Assigning more than half of CPUs for the virtual machine may cause performance degradation for both Mac and VM.

Note:  although Parallels Desktop 16 and earlier allows you to set a custom RAM value, we strongly advise keeping the value a multiple of 1024 (1024, 2048, 3072, etc.), otherwise Windows may behave incorrectly.

2. In Parallels Desktop 16 and earlier Parallels Desktop versions for Mac computers with Intel processors, under Hardware > Graphics set Memory option to Auto (Recommended).

In Parallels Desktop for Mac computers with Apple M1 chip system memory is used for graphics to provide the best experience working with virtual machines. More details can be found in KB 125351

3. Under Options > Optimization set Resource usage to No limit.

4. If your Mac uses an HDD or a Fusion Drive (not an SSD), make sure that the TRIM option is disabled: go to Hardware > Hard Disk > Advanced... > uncheck Enable TRIM option.

5. Start your virtual machine and test performance.

Possible solutions for Windows virtual machines

  1. Install all pending Windows updates. Then restart a virtual machine two-three times to apply changes completely.
  2. Users who use their virtual machines rarely may encounter slowness and other performance issues after starting a virtual machine if it hasn't been used for a long time. From our side, we recommend giving Windows some time to finish doing necessary internal jobs and other required maintenance tasks. If Windows still working slowly, check Task Manager as described below to find out the reason for CPU consumption.

    The virtual machine's CPU consumption directly depends on guest operating system usage. If you notice that your virtual machine consumes a high amount of CPU resources, check CPU consumption in the guest operating system in Task Manager (right-click on Windows taskbar > Task Manager):

    Once you determined what process of Windows program consumes a sufficient amount of CPU, you may refer to the software manufacturer's knowledge base to find more information. For some types of software, like video or photo editing, CAD, or video games, high CPU usage is a common operating condition.

  3. Try to run a clean boot to exclude possible third-party applications influence. 
    Note: in step 3 keep Parallels services enabled. 
  4. Try checking a Windows virtual hard drive as described in KB115549.

Optional

Perform defragmentation on your Windows virtual hard drive as described here

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