@pH 有的，一直都有。

[WindowServer draws everything you see on the screen.](http://forums.macrumors.com/showthread.php?t=59082)

WindowServer (aka Window Manager) Responsible for managing the computer's display and mediating between the various Applications and other processes that want to display information on it. It also does the grunt work of launching new user applications, so most user processes are actually its children in the process hierarchy.

ref: http://www.bivalve.net/reference/OS-X/background-processes.html

小结：10.10 透明磨砂之类的效果较多，估计 windowServer 用的内存和 cpu 较多。
可通过 Accessibility -> Display -> Reduce transparency 减少部分效果

ps：期待更专业的解答。