@ysmina-- I don't have an answer for that. Speed of ejaculation has to do with how much semen is stored. If there hasn't been ejaculation for a while, the speed will be higher.
I have heard a theory that the higher the speed of ejaculation, the easier it will be for sperm to reach the egg, but I'm not sure if that's true. I do believe that frequent intercourse and masturbation slows down sperm however.
It's probably more important to lead a healthy lifestyle, eat well, not smoke, limit alcohol and exercise.