From time to time, specially after not restarting my computer for a few weeks, I get this annoying delay when I want to adjust the volume. I press the key, and the response comes a couple seconds later. I said annoying, but in reality it becomes infuriating real quick.
Thankfully, I learned how to fix it today, and it’s really easy:
In your terminal, type:
sudo killall coreaudiod
You’ll need to type your password after that command. This will kill the Core Audio Daemon, which handles everything about sound in the Mac.
The Core Audio Daemon should restart right away, but if it doesn’t, do this:
sudo launchctl unload /System/Library/LaunchDaemons/com.apple.audio.coreaudiod.plist
This will unload the preferences for the Core Audio Daemon,
sudo launchctl load /System/Library/LaunchDaemons/com.apple.audio.coreaudiod.plist
And this will load them again. Audio will be working at this point, and your volume keys will be as responsive as they should be.