WindowServer using abnormally high amount of CPU power


macrumors regular
Original poster
Feb 14, 2008
I have noticed that with Yosemite GM3, WindowServer seems to be taking up around 30% - 60% CPU (depending on the number of open programs) whenever UI transparency is enabled. I didn't notice this kind of behavior in Mavericks.

Turning off transparency drops it to around 8% but it was usually less than 1% in Mavericks.

This is on a Mac Pro with D700s, it doesn't happen on my Macbook Air with Intel HD 5000 graphics.

Can anyone else confirm this?


macrumors newbie
Oct 20, 2014
I'm having trouble with high CPU usage by WindowServer.

How do you disable transparency?


macrumors 6502a
May 7, 2009
I'm having the same issue on an early 2011 MacBook Pro. This only happens when an external display is connected - it doesn't happen when only using the internal display.

I've noticed that it gets worse and worse every time the Mac switches between integrated and discrete graphic card (at least I think that's what triggers it), ie. when connecting and disconnecting the external display. It would probably help if I forced it to always use the discrete card using gfxCardStatus, but that decreases battery life when I'm using it on the road.

Disabling transparency also reduces the issue, but the non-transparent dock is just plain ugly. It would be nice to be able to only make app windows non-transparent, but I haven't found a way to do it (there surely is some "defaults write" command to do it, but nobody documented it yet).

At the end, I think this is a bug, but until I can't find a way to reproduce it reliably, I can't really report it to Apple.

If anyone has any information on how to reliably trigger the issue on a freshly booted system, please post in here :)
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.