How to manage WindowServer CPU usage

2.1K views
4 min read

Most of the time, you don’t think about processes that are active on your Mac in the background. You work with apps, but don’t consider things like synching, indexing, and network connectivity — all of which are necessary for your Mac to work properly. 

Occasionally, you might notice that your Mac is running slower than usual. You take a peek at the background activity and discover that a WindowServer process is taking up a significant percentage of your CPU. 

You might wonder what is WindowServer? Why do you need a WindowServer Mac process and how to make sure it uses less of the CPU and RAM available. Let’s find out.

What is WindowServer Mac process

WindowServer is a core process of your macOS, connecting all your interface applications and actions to your display. So if you see something on your Mac — WindowServer was involved in it being shown. 

Basically, WindowServer draws all the graphical elements and keeps track of all the changes for window positioning, desktop icons, fonts, Spaces, animations, visual effects, etc. It’s also responsible for all the external displays. Every time you open a new window, switch to a different tab, or tweak a photo, WindowServer is actively redrawing your screen. 

On most recent Macs, the WindowServer process is designed to run in the background without you ever noticing. It’s a completely safe (and essential) process to leave running. But, sometimes, you might find it misbehaving. 

Why WindowServer uses so much CPU

In some rare cases, your WindowServer process could spin out of control and eat up 30 to 50% of your CPU. Why does that happen? 

The spike in WindowServer activity could be legitimate and caused by your increased activity — video editing or gaming, for example, or something else that requires redrawing the screen quickly. 

Another reason for the WindowServer process to spike is a bug in the app you’re currently using that could cause constant refreshing. 

More long-term increases in WindowServer activity could be due to working on multiple high-resolution (e.g. Retina) displays, having a cluttered desktop, and using lots of macOS effects, such as transparency and drop shadows. Older Macs have an especially hard time processing modern visual effects. 

How to track WindowServer CPU usage

If you want to keep track of how much CPU the WindowServer process is using at any given moment you can do so with the default utility called Activity Monitor:

  1. Launch Activity Monitor from the Utilities folder in Applications
  2. In the CPU tab, search “WindowServer” 
  3. Take note of the CPU percentage the process is currently consuming

track WindowServer process with Activity Monitor

Note: Don’t try to quit the WindowServer process like you would do with other tasks. This process is essential to system performance and will just open right back up, likely with the same CPU load.

App Tamer is an even better way to manage WindowServer. This lightweight but powerful utility lives in your menu bar and monitors every process on your Mac, so you don’t have to keep Activity Monitor open all the time. What’s more App Tamer allows you to set limits for how much CPU every task can be consuming. 

For example, to limit your Safari CPU usage: 

  1. Launch App Tamer
  2. Click on Safari in the list of processes
  3. Check “Slow down this app if it uses more than:” 
  4. Enter the max CPU percentage allowed

manage WindowServer process

How to lower WindowServer CPU usage

In case WindowServer is really taking up lots of CPU on your Mac for an extended period of time, you can try a few things to tame it down. 

Quit all unnecessary applications. If you have multiple applications open at the same time, WindowServer would have to redraw them all with every interaction. As you close your apps, monitor the change through App Tamer and you could find the one responsible for most of the CPU hogging.

Close the windows you don’t use. Every extra window adds weight to the WindowServer process. So make sure only the ones relevant to what you’re doing are open. You could also try merging separate windows into tabs. The same goes for a number of desktops in Mission Control.

Speaking of Mission Control. To make this function even more useful on Mac, you need to have Mission Control Plus. 

Mission Control Plus is a small utility that adds the close button to all the windows in Mission Control, making closing them a breeze. It also provides you with handy shortcuts for closing, opening, and minimizing windows as well as quitting apps. 

add the close button to all the windows in Mission Control

Use fewer monitors. Do you really need to have a few Retina screens going on at once? Consider switching off some monitors when you don’t use them to give the WindowServer process a break. 

Reduce transparency. There are lots of visual effects on Mac that you can tweak to use less CPU, but transparency is a big one. To turn it off, go to System Preferences ➙ Accessibility. Move over to the Display tab and check “Reduce transparency”.

Reduce transparency

Delete login items. When you start up your Mac, there might be a lot of processes loading at once: all the utilities and apps you use. It’s a good idea to review the login items from time to time, to see whether there’s anything you don’t need: 

  1. In System Preferences, go to Users & Groups
  2. Select the user and then switch to Login Items
  3. Use the minus icon to delete any unwanted processes

manage login items

Optimize your Mac. The best way to keep your Mac in shape year-round is to use an app specifically made for this purpose — CleanMyMac X.

CleanMyMac X is the easiest way to keep your Mac working at top speeds. This app’s Maintenance module can take your Mac from slow to race-ready in seconds, with options to free up RAM, run maintenance scripts, repair disk permissions, and more. Along the way, CleanMyMac X would check your machine for any malware that could have influenced WindowServer as well and delete any junk files.

To improve your Mac with CleanMyMac X: 

  1. Launch CleanMyMac X 
  2. Navigate to the Maintenance tab
  3. Check all the scripts you want to use
  4. Click Run
  5. Repeat with Malware and System Junk tabs

macOS maintenance utility

Update your software. Old Mac apps can run slower than their newer and more optimized versions, so make sure to check the App Store and individual apps for updates. At the same time, go to System Preferences ➙ Software Update to see if there’s a new macOS version available. Finally, if nothing works — try to restart your Mac.

check macOS for updates

As you can see, managing the WindowServer Mac process is easy, especially when you have the right tools to do so, such as App Tamer, Mission Control Plus, and CleanMyMac X

Best of all, App Tamer, Mission Control Plus, and CleanMyMac X are available to you absolutely free for seven days through the trial of Setapp, a platform with more than 210 top-class Mac apps ready to take on any task you can imagine. Try the whole Setapp collection today at no cost and pick your new favorite tools. 

Get 220+ Mac apps for any job

Sign up to Setapp and try them for free.