Go to the Cheat menu under Extras and put in the code DINGO.

When you get to the harder levels, you will find out that Dessan (Dark Jedi) had
followed you to the Valley of the Jedi and was giving his fighters the power of the
Force and created fake Jedi. You will have to fight these people throughout the
game. If you do not want to waste your time fighting them, then use Force Speed.
You will move incredibly faster than your opponent and can attack them while his
lightsaber is going too slow.

After you get Force Grip, use it and Saber Throw to kill the "fake" Jedis. This take
longer as you progress in the game, but it still works.

To kill opponents faster, change your lightsaber mode to red (strong).