  We report a consequence of the orbital angular momentum (OAM) of a beam to
its group velocity. We calculate the group velocity $v_g$ of Laguerre-Gauss
beam ($\emph{LG}$) with $\ell$ and at $p=0$. The $v_g$ reduction of $\emph{LG}$
beam even in free space is observed to have dependence on both orbital or
winding number $\ell$ and the beam's divergence $\theta_0$. We found that light
possessing higher $\ell$ travels relatively slower than that with lower $\ell$
values. This suggests that light of different OAM separate in the temporal
domain along propagation and it is an added effect to the dispersion due to
field confinement. Our results are useful for treating information embedded in
light with OAM from astronomical sources and/or data transmission in free
space.
