Planets acquire their rotation when they are formed, taking angular momentum from the impacts that shape them.
There is a relationship between the mass of a planet and the speed of its spin, except where tidal forces have decelerated planets and made their days longer.
At between 8 million and 20 million years old, the Beta Pictoris system, 63.4 light-years away, is still in its formative stage. Young planets are still accreting as planetesimals collide in the debris disk that surrounds the star.
Source SPACE.com: All about our solar system, outer space and exploration.