How to reduce WindowServer’s CPU usage on your Mac

One of the most important macOS elements is the relationship between the calculations carried out by the CPU and what you see on screen. That relationship is managed by WindowServer on your Mac, a process that is responsible for drawing graphical elements on display.

Most of the time, you won’t have to think about it or even know it exists, but if it starts using lots of CPU cycles, it may slow down your Mac. Here’s how to fix that.

What is WindowServer on Mac?

Simply, it’s the macOS process that draws elements on the screen, whether they are application windows, icons, or websites. The more windows you have open at any one time, the more CPU cycles WindowServer needs. Most graphical elements are refreshed regularly, which is why WindowServer needs those CPU cycles. Every time you move a window around or edit an image in Photoshop, or switch to a different tab in Safari, WindowServer needs to redraw your screen.

When you consider that windows in macOS have lots of effects, such as transparency and drop shadows, it’s hardly surprising that drawing and redrawing them on screen consumes resources. However, on most Macs, the number of CPU cycles WindowServer consumes should be so small you don’t notice it.

Why does it use so many CPU cycles?

There are a few things that can cause WindowServer to use so many CPU cycles that you notice it or that it slows down your Mac. These include:

  • Applications misbehaving
  • Having multiple displays
  • A desktop cluttered with icons (each of these has to be redrawn every time the screen contents change)
  • Older Macs that are running the most recent version of macOS and struggling with some visual effects.

How to find out if WindowServer is using excessive CPU cycles

  1. Navigate to Applications > Utilities and launch Activity Monitor.
  2. Click the top of the CPU column.
  3. Look at the names of the processes in that column.
  4. If WindowServer is near the top and takes up more than 60% of CPU resources, you know it’s using more CPU cycles than it should.
  5. Quit Activity Monitor.

Is WindowServer related to mds_stores?

No, not directly. While WindowServer controls the drawing of elements on the screen, mds_stores on your Mac (mds stands for metadata server) is part of Spotlight. If you see mds_stores consuming CPU cycles, it’s probably because Spotlight is reindexing your Mac.


If you find that your Mac is struggling and often runs slowly, CleanMyMac X’s Maintenance Module can help. It runs several routines, including freeing up RAM, running maintenance scripts, and repairing disk permissions that can improve your Mac’s performance. Its System Junk module will also identify and remove junk files that are littering your boot drive and may be hampering performance. Here’s how to use it. 

1. Download and install CleanMyMac X, then launch it. 

2. Choose System Junk and press Scan. 

3. When it's finished, press Clean to get rid of the files it has found or Review Details to find out more.

How to lower WindowServer CPU usage

1. Close windows you don’t need

      The more windows you have open, the harder WindowServer has to work, especially if you have an older Mac. You should also close browser tabs you’re not using, as this will reduce the overall load on your system. And if there are any applications open that you are not using at the moment, quit those (press Option-Command-Escape to open the Force-Quit menu). 

      2. Turn off visual effects

      Features like transparency in windows also use more CPU cycles. You can’t turn off every visual effect, but you can switch off transparency using the Accessibility pane in System Preferences. To turn it off:

      • Go to the Apple menu and choose System Preferences.
      • Click on Accessibility and select Display.
      • Check the box next to Reduce transparency.

      3. Reduce the number of desktops in Mission Control

        Closing additional desktops may help lower down WindowServer CPU usage:

        • Press the F5 key to invoke Mission Control or, if you’re using a non-Apple keyboard, click on the Launchpad icon in the Dock and choose Mission Control.
        • Hover the mouse pointer over any desktops you are not using.
        • Click on the ‘x’ in the corner of the desktop to close it.

        4. Check if apps are up to date

          For apps downloaded from the App Store, launch the App Store app and check the Updates section. For other apps, launch them, click on the app name in the menu bar and choose Check for Updates.


          CleanMyMac X can check all the apps on your Mac for new versions and install any available updates. It’s much quicker and easier than installing patches individually.

          5. Check if macOS is up to date

            Click on the Apple menu and choose About this Mac and click on Software Update. If there is an update available, install it.

            6. Restart your Mac

              Many of us don’t restart our Macs very often; we just close the lid when we’re finished working and then open it again when we need to use our computer. However, restarting is important to free up RAM and delete caches and other temporary files. It can also fix problems like certain processes occupying too many CPU cycles.

              WindowServer is a process that controls the drawing of graphical elements and windows on your Mac’s display. Under normal circumstances, it should take up so few system resources you won’t notice that it’s running. However, occasionally things can go wrong, and it consumes way more CPU cycles or RAM than it should. If that happens on your Mac, follow the steps above to reduce the resources it uses.

              Laptop with CleanMyMac
              CleanMyMac X

              Your Mac. As good as new.