Why WindowServer Uses High CPU & Memory on MacOS Tahoe and How to Fix It
If you have felt your Mac is curiously sluggish, you may have opened Activity Monitor to investigate at some point and noticed a process called “WindowServer” using a large amount of CPU or memory. High CPU usage and memory consumption of WindowServer has been a long reported issue on MacOS with various system software versions, but a resurgence of new complaints about WindowServer have surfaced with the release of MacOS Tahoe. Some Tahoe users feel that WindowServer is using excessive amounts of system resources, leading to sluggish behavior, poor performance, laggy animations and interactions with the user interface, and even excessive battery drain.
WindowServer is a core part of MacOS, and these complaints are often justified, but it’s important to understand what is likely causing the problems with WindowServer resource usage, and what you can do to manage it. Let’s dive in and learn more about the WindowServer process, what it does, and how to troubleshoot its resource usage.
What is WindowServer anyway?
WindowServer is a system level process of MacOS that is responsible for drawing everything you see on the screen. This includes things like windows, apps, the entire interface, animations, transitions, menus and dropdowns, the Dock, transparency, visual effects, and even external display rendering.
Basically every visual element you see on the screen passes through and is handled by WindowServer.
And this is where performance comes into play, because the more work that your Mac must perform to manage what is on the display, the more resources WindowServer will use.
Why WindowServer Uses High CPU or Memory
The biggest reason why WindowServer can use a lot of CPU or memory is because the Mac has a lot happening on the screen. This usually means many concurrent open windows and apps, all the visual effects (and the Tahoe Liquid Glass interface is heavy on visual effects), perhaps multiple displays, many open browser tabs or windows, and more.
Since not all apps are perfectly optimized, and web browsers in particular are notorious for memory leaks and excess resource consumption, many users can find that WindowServer goes haywire with excess resource usage when many web browser tabs or browser windows are open, regardless of what the browser is. Whether it’s Safari, Chrome, Firefox, Brave, Epic, Edge, etc, all can succumb to the same set of performance issues within tabs and windows, that then cause a spike in WindowServer resource use.
Additionally, for drawing the Liquid Glass interface on macOS Tahoe, some users have also noticed that UI changes and effects can increase WindowServer workload, especially compared to prior MacOS versions that did not have the Liquid Glass UI shine and effects. This can be a contributing factor as to why some users feel macOS Tahoe is slower than prior system releases.
How to Reduce WindowServer CPU & Memory Usage on Mac
We’re going to offer some general tips and advice on how to reduce the WindowServer CPU usage and memory consumption. These are not necessarily specific to MacOS Tahoe, and they should help on basically any version of MacOS that is experiencing heavy WindowServer resource use.
1: Close Unnecessary Apps, Windows, & Browser Tabs
The simplest and most direct fix is often the most effective, and that is simply closing unnecessary or unused apps, windows, and browser tabs. Fewer open windows, apps, and tabs, leads to less rendering overhead, reducing resource usage.
- Close out of any unnecessary or unused apps
- Close unnecessary and unused windows for apps
- Close and reduce the number of open browser tabs and browser windows, regardless of the browser itself
These three alone can dramatically lower WindowServer activity and resource usage, and you often will see near immediate results and improvements to performance.
2: Reduce Transparency & Visual Effects on the Mac
Next up is reducing the amount of visual effects that are in use on MacOS, since every transparency, blur, animation, and transition, requires extra GPU, CPU, and memory to draw and render on the screen. These are Accessibility features you can toggle off:
- Open “System Settings” from the Apple menu
- Go to “Accessibility” and then to “Display”
- Toggle the setting for “Reduce Transparency” to ON to eliminate many of the translucent visual effects
- Next return to “Display” settings and go to “Motion”
- Toggle the setting for “Reduce Motion” to ON to dramatically reduce the animations drawn on screen when interacting with the Mac
These two settings can significantly reduce WindowServer load, especially on older Macs, but even on many newer M-series Macs they will make a difference too. Personally I just use “Reduce Transparency” on my M-series Mac, but you can try both, or either, to see what works best for you.
Note that “Reduce Transparency” was broken and ineffective for multiple versions of MacOS Tahoe, so you will want to make sure you are updated to the latest system software version of MacOS Tahoe to be able to effectively use that Accessibility feature.
3: Not Using an External Display? Disconnect It
Some users have found that having multiple external 4K or 5K displays connected to their Mac can cause a spike in WindowServer activity and resource usage. If you aren’t heavily relying on an external display, consider disconnecting it from the Mac.
It’s also easy to get carried away with dozens and dozens of open apps and windows when you have multiple displays connected to a Mac, so remembering the first tip mentioned here, be sure to close down any unnecessary apps, windows, or browser tabs, on any external displays.
4: Check for Resource Monitoring Tools & Apps
If you’re the type of Mac user who likes to use live resource monitoring (like running an open instance of Activity Monitor itself, or even tools like Stats and command line tools like htop), you might find that closing those apps or resource monitors can reduce WindowServer activity as well.
One telltale sign that a resource monitor is, ironically, itself causing a CPU/memory resource issue, is when you see that process directly, or ‘sysmond’, within Activity Monitor, consuming a lot of CPU or memory.
5: Focus on Resource Heavy Apps
This is a variation of the first tip, but focusing on specific apps that are known to cause a lot of resource usage even if they only have a single app window. For example, a Safari window with a hundred open browser tabs, or even a video playback or video streaming app. Perhaps you are letting a game like “Civilization 7” run in the background on the Mac, in which case quitting that game will likely provide a reduction in WindowServer use.
Quit out of any suspected apps while watching in Activity Monitor, and you might just find that WindowServer resource use drops dramatically.
6: Update MacOS & Your Apps
Updating all of your apps, and updating MacOS itself, can also resolve known bugs or issues with app resource usage, and even WindowServer. As mentioned earlier, several versions of MacOS Tahoe had broken the Reduce Transparency feature, whereas newer versions fixed that issue, and made toggling the feature more effective at reducing CPU and memory of WindowServer.
Update your apps through the Mac App Store, and any individual app directly (like Chrome or similar browsers).
You can update MacOS through System Settings > General > Software Update.
7: Restart the Mac
A good old fashioned system restart can make a dramatic impact on WindowServer usage, because a restart basically wipes the existing slate clean. Any potential memory leaks or rendering issues will be cleared, and you’re starting fresh again.
The easiest way to restart a Mac is through the Apple menu > Restart.
A restart will almost certainly improve things in the interim, but just remember to be mindful of the other tips mentioned here after a restart, and keep the number of apps, windows, tabs, and eye candy to the essentials.
When High WindowServer CPU & Memory Usage is Normal on Mac
It’s important to point out that WindowServer using a lot of CPU or memory is not necessarily because of a problem, and in fact it may be high because of your specific workload demands.
If you’re engaging in a heavy workload on the Mac, it is normal to experience a lot of resource usage, taxing the CPU, GPU, and memory. This includes situations where you’re using many apps at once, have dozens or hundreds of open browser tabs, you’re watching videos or animations, you’re rendering or exporting video or animations, you’re playing resource heavy games, and many other common power user and pro user level system activities.
Heavy computer usage is expected to lead to heavier resource usage, and WindowServer is no exception. You should expect short bursts of heavy usage to cause increases in WindowServer CPU, GPU, and memory usage, and it’s really only when WindowServer is getting hammered for inexplicable, unusual, idle, or light tasks, that warrant additional troubleshooting.
Constantly Hitting WindowServer CPU & Memory Usage Problems? Consider Upgrading the Mac
If you’re always running into problems where WindowServer is using obscene amounts of CPU and memory, you might consider the possibility that your workflow demand is more than your specific Mac can handle.
This is more common to experience for users of immensely resource intensive apps and workflows, users of lower end models, and older Macs, but even a brand new MacBook Air could theoretically struggle under certain rigorous usage conditions, and a symptom of that could be WindowServer going wild. If this is happening to you regularly, and you’ve performed all the troubleshooting steps outlined above, you might simply have a workflow that is too demanding for your current hardware, and you might consider upgrading to a more powerful Mac.
For example, if you consistently struggle with performance on a MacBook Air base model, consider an upgraded MacBook Pro with more RAM and CPU power as your next Mac. Fortunately Macs have great resale value, so even if you purchased a MacBook Air recently, you should be able to recapitalize that expense and put the proceeds towards a new upgraded and more powerful Mac.
Things to Avoid That Will NOT Help Heavy WindowServer Resource Usage
We have covered what will help, but won’t help? Well, there’s some unhelpful advice out there too:
Avoid Cleaner, Antivirus, & Speed Boost Apps: There are endless scams on the web nowadays unfortunately, and many of those scams and unscrupulous actors involve ‘cleaner’, “anti-virus”, and ‘performance’ type of applications, often that are paid to use, or with some dubious subscription model, or that claim to perform miracles on Mac performance. Again, these are often scams, and no amount of ‘cleaner’ or ‘antivirus’ apps will resolve a WindowServer resource usage issue. If they do, it’s probably just coincidental, and they’re probably just quitting open apps and performing tasks similar to what we’ve outlined here. To be clear, not all of these apps are scams, but there are so many scams in this area that they’re generally best avoided.
Avoid Killing WindowServer Process: Do not target or kill the “WindowServer” process directly on the Mac. All this does is force everything on the screen to redraw, leading to another spike in resource usage. The better approach is to simply close out of unnecessary windows and apps, and then restart the Mac, which will naturally and gracefully restart WindowServer and reduce resource usage.
In Summary, WindowServer is Essential, Resource Use Depends on Mac Usage
Because WindowServer is responsible for rendering the entire macOS interface and everything you see on the screen, its resource usage is closely tied to how you use your Mac. This is important to remember as you manage and work with WindowServer, and troubleshoot any potential issues.
By reducing visual effects, limiting open windows, apps, and tabs, keeping your MacOS and apps up to date, and optimizing display usage, you can often bring high WindowServer CPU and memory usage back down to normal levels.
And by the way, issues with WindowServer are not a new complaint. While many users have reported that WindowServer has issues with MacOS Tahoe, it turns out that there have been usage related issues with WindowServer going back a long time, and we first covered a collection of tips to troubleshoot these problems over a decade ago, and many of those tips still hold up!
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What has been your experience? Have you noticed unusually high WindowServer activity or resource usage on your Mac? Has it gotten better or worse with macOS Tahoe? Did you work through the steps above, and did you find noticeable differences in performance, resource usage, and responsiveness? Did you find another trick or solution to fix the problem? Share your experiences, thoughts, and relevant commentary below!
