The Pluto mission definitely isn't a Hoffman Minimum Energy transfer
If it were, it'd probably take about 15 years or more to get to Pluto. Voyager took 12 years to make it to Neptune and Pluto is further out. The mission could take even longer if there weren't a favorable planetary alignment to take advantage of slingshot maneuvers.
It'll be fun to watch the actual liftoff. From hold down release, the rocket will be accelerating at approximately 2 Gs, the fastest of any space launch that I can remember. It'll hit Max Q (maximum dynamic pressure, typically around Mach 1) in less than 30 seconds after liftoff. That's moving!