Why are my sounds lagging on my 13" Macbook Pro?
I would RESET the Notification app:

Open the Library folder in your Home folder. Hold the &quot;alt&quot;key and use GO in Finder that will show you the Library folder

In the Library folder, open the Application Support folder.

Locate the folder named NotificationCenter. Drag this folder to the desktop.

Next, open the Terminal application.
Copy and paste each line of these commands into the Terminal window, in order. Press return after each line:
cd getconf DARWIN_USER_DIR
rm -rf com.apple.notificationcenter
killall usernoted; killall NotificationCenter

Close the Terminal app.

Restart your computer.


WARING: be very careful with the rm-rf part and make 101% sure you copied the correct text.