As with previous versions of windows, it takes longer to restart or shutdown the computer when the "Exit Windows" sound is enabled.
To remove the sound effect (and slightly imporve shutdown/restart time):
Start
settings
control panel
Sound,Speech and Audio devices
Sounds and Audio Devices
Sounds
"Program events" (bottom half of the window) lists the available windows functions that you can assign sound effects to.
Scroll down until you find "Exit Windows" and left click on it once to highlight it. Now look to the bottom of the window for "Sounds", click on the black arrow on the right and then select "(None)" from the drop-down menu.
Click the "Apply" and then "Ok" buttons to complete the process.