Luke sure made it from the North Pole to an equatorial docking bay dragging a dying giant of an armored man pretty darn quick.
The Emperor has a direct elevator between the Throne Room and a hallways somewhere near that docking bay, though it can also go to Vader’s meditation chamber (location unknown). Unfortunately, this is only found in a few deleted scenes:
- Vader uses the elevator to get to his meditation chamber
- Vader wants to use the elevator to visit the Emperor
- Vader takes Luke from the shuttle to the elevator to go up to the Throne Room
Unfortunately, this final scene is the only one that would come close to showing the geometry of this problem, and it’s the only one of those three that’s never been released. Either way, Luke does have to drag Vader down a hallway, which is maybe stretching credulity. On the other hand, he can use the Force.