WindowServer is a process on Mac that controls the drawing of graphical elements and windows on your Macs display. It is responsible for processing the graphical elements you see on your Macs screen, including application windows, icons, and websites. Whenever you move a window around, edit an image in Photoshop, or switch to a different tab in Safari, WindowServer needs to redraw your screen. 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.

WindowServer is not a virus and poses no threat to your Mac. However, it can use up a lot of CPU, which can slow down your Mac. 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, including misbehaving apps, editing images in Photoshop or another editing software, opening multiple windows at a time, a cluttered desktop, and apps with junk files.

If you notice that WindowServer is using too much CPU, there are several ways to reduce its CPU usage. These include closing unnecessary windows, reducing transparency and animations, disabling separate spaces per desktop, and restarting your Mac. You can also use the built-in macOS utility called Activity Monitor to check how much CPU the WindowServer process is using.