FBI tests indicated 2.3 seconds was the minimum amount of time to fire an aimed shot. While theoretically possible, it is hard to believe that Oswald would rush his shot that quickly. He would have understood that accuracy was far more important the speed. He had only one more round left after that shot so he would want to make every shot count. One well aimed shot gave him a better chance of succeeding than two rushed shots would have. There was 4.9 seconds between the two shots that hit JFK. That's more than double the theoretical minimum so clearly Oswald was taking careful aim before squeezing off the fatal shot.
