I recently met some friends at Five Guys for lunch. This restaurant can be very busy at lunch as it is in a business district. However, they get people in and out fairly quick. They have great burgers which you can get almost any type of condiment on it. I'm glad that they've started serving a smaller fry. You may read other post about how many fried you get, but now they have a "little" fry which is more in line of a serving for 1 person.
While I didn't do it I saw a sign, and talked to an employee, about calling your order in ahead of time OR ordering online to save time. I think this is a great service to have for customers that need to get back to work quickly.