By move 20 you were up a rook and an exchange and from then until the end of the game the computer wasn't able to make a single threat.
So... my impression is that it's not hard.
By the way, rook vs minor piece trick is often to sac the rook at the right time. 38...Rxe5 and I bet you could win in your sleep.
This CPU easy seemed to be playing way out of its league. I felt like I had to make GM moves to win this game.
http://www.chess.com/livechess/game?id=1016346895
How is this "easy"?