How to use "performing" in a sentence

Sitting in the dark theater, he smiled, not at the comic magician who was performing in front of the closed stage curtains, but at his own sudden, youthful exuberance.

Two uniformed security men were performing first aid on the unconscious man, loosening his tie and collar, taking his pulse, while a third guard was keeping curious customers out of the way.

But no human being saw as much of them as I did and lived to tell the story, and I can say that I have seen four, five or six of them slowly performing the most difficult work without sound or any other signal