JavaFX Smooth Key Events

I am making a ping pong game using JavaFX, but before I am going to make that, I like to test the KeyEvents.
I made a simple ping pong game about 2 years ago, but I like to improve my game.
And was pretty bad controlls back when I made the ping pong game, because of the not smooth controls.

so here is the problem:
whenever I holdpress A and switch quickly to holdpress D or D to A, same with (W to S and S to W).
it just takes a little break and then move, is there something I can change, improve?
I don't know why it does this.