This seems like a fairly typical coaster construction pace to me. Much of the ride constructed thus far has been low to the ground columns. They can be put up quickly and don't require a special crane to do so. Also, keep in mind that they started ground work for this around the time that Hagrids opened. On Disney's side of the fence, the actual coaster portion of Tron went up quickly, but realize how much groundwork was needed beforehand and how they're rerouting the railroad and building an enormous show building around the ride as well. It's a similar story with Guardians of the Galaxy - for all we know, track work could have been complete inside the show building over a year ago but we wouldn't know...but don't forget how much theming and other work must be done inside the show building before it's complete.