Some of my favourite time-wasting barbs:
“You have too much time on your hands” – when you refuse to look busy.
“You are wasting your time” – when the value of the task is unclear to the observer, at least.
“It’s your time you are wasting, not mine” – when appearing to be “out of control.”
No one has more time than anyone else, we all have 24 hours a day. How you spend it is up to you.