I really don’t see how it improves the pacing. If anything I’d say it has a negative effect on it. You spend way too much time away from the main villains to the point where you start to wonder what’s going on with them. The way it is in the final movie is perfect. You’re shown what the villains are doing, and then after the first sequence with the heroes we are updated with the status of the villains.

Plus the Vader scene is great and helps give build up to the Emperor’s arrival.