The Serbian world number one thrashed Frenchman Paul-Henri Mathieu 6-1 6-3 6-0, staying on court for just one hour 28 minutes on a warm day at Flushing Meadows.
Djokovic believes his game is at a good enough level that finishing matches off quickly has become the key.
"Since I have nothing to complain about, I wanted to get my job done as quick as possible," he said after his second-round win on Thursday.
"I don't feel like I need to play long matches to get into the groove. I mean, I feel that I'm hitting the ball very well. Second match even better than the first one.
"Under the circumstances I think I came up with a very good performance.
"[I] stayed mentally tough and not allowed myself to get frustrated because of the wind and conditions that were obviously very tough for both of us."
Djokovic expects his tournament to get tougher, beginning with a clash against American Sam Querrey.
The seven-time grand slam champion has a 7-1 win-loss record against Querrey, who eased past Spanish 28th seed Guillermo Garcia-Lopez.
"Sam is playing in front of his crowd. I'm sure that he's going to have some good support," Djokovic said.
"But on the other hand, if we get to play on centre court maybe night session, that's where my experience kicks in, I think.
"I have had a lot of matches, night sessions if we get to play, as I said, and try to neutralise his serve that is his big weapon. If he serves well he's very dangerous.
"I saw a little bit of his match today and he played great. He's in good form, good shape, and has nothing to lose. It's going to be a tough one."