One of the more common complaints about OS X Yosemite is that it appears to run slowly for some users; however, this is not because it is always slow. In many cases, the OS runs just fine but then will run into a period of intermittent but frequent pauses where input like clicks and typed text will halt and the system may show the spinning color wheel. This is followed by all of the paused activity suddenly catching up with itself a few moments later.
If you have upgraded to OS X Yosemite and are experiencing this issue, then it is very likely from a common bug in the OS X WindowServer that results in system console messages similar to these (the Console app is in the Applications > Utilities folder):
08/01/15 20:40:51,204 WindowServer: disable_update_timeout: UI updates were forcibly disabled by application "TextEdit" for over 1.01 seconds. Server has re-enabled them. 08/01/15 20:40:51,828 WindowServer: common_reenable_update: UI updates were finally reenabled by application "Finder" after 1.23 seconds (server forcibly re-enabled them after 1.00 seconds)
Beyond this approach, there seems to be little you can do, but since it can’t hurt, you might as well do a quick maintenance routine on your Mac to ensure everything is running as smooth as possible:
- Reboot into Safe Mode by holding the Shift key at startup
- Use Disk Utility to perform a permissions fix on your boot drive
- Shut down your Mac and Reset your Mac’s SMC
- Start up your Mac, but immediately hold down the Option-Command-P-R keys to reset the PRAM (release the keys when your system auto-reboots)
When this is done, you will have reset various hardware variables and checked for filesystem setup issues on your Mac, that while likely benign, might be contributing to the problem.