Why Is WindowServer Using So Much CPU?

WindowServer draws everything you see: every window, menu, shadow and animation. When it climbs in Activity Monitor, the Mac is working hard to paint the screen. The fix is to give it less to paint.

What WindowServer does#

1. 1Apps

   Each app sends its window contents.

   ↓→

2. 2WindowServer

   Combines windows, shadows, blur and animation into one picture.

   ↓→

3. 3Graphics chip

   Does the heavy drawing.

   ↓→

4. 4Display(s)

   Shows the result many times a second.

What is making it work hard?#

Match your setup to the likely cause

What is the biggest change to your setup?

I added an external display, or more than oneEverything looks blurry and animated: lots of transparency and motionOne app or web page seems to trigger itNothing changed. It has always been like this

The settings that matter#

WindowServer relief checklist

• Reduce transparency System Settings → Accessibility → Display.
• Reduce motion Same screen. Cuts animations and transitions.
• Lower the external display's refresh rate System Settings → Displays, if the monitor offers more than one rate.
• Use a lower scaled resolution on very large displays
• Close windows and Spaces you are not using Fewer windows means less to combine.
• Close web pages with autoplay video or animation
• Restart the Mac and install updates

How to confirm the fix worked#

1. Open Activity Monitor → CPU and note WindowServer's percentage before.
2. Change one setting from the checklist.
3. Wait a minute with the screen still, and compare.

Change one thing at a time. If you change five, you will not know which one helped.

When it looks like a bug#

If WindowServer stays high with a single display, reduced transparency and no apps open, update macOS, then try Safe Mode. If it calms in Safe Mode, a login item, extension or screen utility is involved. If it is still high, contact Apple Support, and say which Mac, display and macOS version you use.

Frequently asked questions#

Can I quit WindowServer?#

No. It manages your display, and quitting it logs you out. Reduce the load instead.

Why did WindowServer spike after I plugged in a monitor?#

More pixels and a higher refresh rate need more drawing. Lower the refresh rate or resolution to test.

Does Reduce Transparency hurt my Mac's looks?#

It makes menus and sidebars solid instead of translucent. Most people stop noticing within a day.

Is high WindowServer usage a sign of malware?#

Rarely. The cause is nearly always display or app load. If you are worried about an app, read how to check that a Mac app is safe.