What does the word flit mean in Catcher Rye?

In The Catcher in the Rye, the word "flit" is used to describe someone who moves quickly and lightly, often in a nervous or restless manner. For example, when Holden Caulfield is in the hotel lobby, he describes the elevator boy as flitting "up and down with the car." This suggests that the elevator boy is moving quickly and efficiently, but also perhaps with a sense of nervousness or anxiety.

It is often related to birds moving between places.