If you're bored with the slow pace of the last kill in a battle, then you should read this page of the Songs of Conquest game guide.
While the "finisher" when defeating the last enemy unit in a battle can be an interesting and enjoyable sight, it can become a bit boring after a few hours of playing. Fortunately, the developers have provided players with the option to turn it off.
To do this, simply enter the menu (esc key) and select Options. Then uncheck the show last battle kill in slowmotion button.