Definitely if you are doing it after the Star Wars fireworks, walking will be your fastest option. People flood out of the park after that, so the lines for boats, buses, and the vehicle line to drive out can be long. Being in the Star Wars dessert party viewing area, you won't be one of the first ones out of the park, so the lines will probably build before you get out. If you happen to get out and there is not really a line for the boat yet and the boat is there or pulling up, it usually takes about the same amount of time as walking- but you would have to be really lucky to hit it just right and not to have a line in front of you so long that you don't make the first boat. One of the things we like about staying at YC is that we can just walk from DHS and EPCOT at the end of the night.