UI Lag/ System beeping 3 times and taking more than usual on shutdown (How to Prevent)

Try rebuilding the PS4's database via the safe mode menu.

https://www.playstation.com/en-gb/get-help/help-library/system---hardware/power---system-stability/safe-mode-on-playstation-4.ps4/

Internet connection could be a factor whilst your PS4 is shutting down it is uploading save data if you have a PS+ subscription.A friend of mine with a slow internet connection has found logging out instead of switching off will force the save data to upload,after a minute he'll switch off completely this avoids the triple beep shutdown.