The speed is relatively consistent except for the early frames (where pictures were taken at twice the rate of later on) and where frames were dropped due to missing data or alignment failure. Here's a version of the animation where frame duration is proportional to the real time between the frames:

http://i.imgur.com/ncTIdHL.gif

The animation spans 3 months or so. The real time is shown in the text in the corner.

Each orbit of Pluto and Charon around each other takes 6.4 days. This is speeded up by a factor of a lot.