When my 2011 iMac's display shuts off - before the computer goes to sleep, but after a screensaver might display - there is frequently a 5-15second delay with the display coming back.
What I see is the backlight on the display come on, showing a completely black screen with the only exceptions being my cursor and any notifications in the upper-right that have appeared since the display shut off.
I can move the cursor around without trouble. I cannot interact with the notifications.
After a delay the rest of the display returns: the dock, open windows, etc... exactly as I left it.
I have only experienced this issue for the last 2-3 months. Is there a way to stop this delay? What causes this?
I see the following in the activity console.
10/8/14 1:04:59.000 AM kernel: PM notification cancel (pid 129, screens_connectd) 10/8/14 1:05:09.872 AM WindowServer: CGXDisplayDidWakeNotification : posting kCGSDisplayDidWake 10/8/14 1:05:09.873 AM WindowServer: handle_will_sleep_auth_and_shield_windows: Deferring.