  The self-energy of a moving vortex is shown do decrease with increasing
velocity. The interaction energy of two parallel slowly moving vortices differs
from the static case by a small term $\propto v^2$; the "slow" motion is
defined as having the velocity $v<v_c =c^2/4\pi\sigma\lambda$, where $\sigma
(T)$ is conductivity of the normal excitations and $\lambda (T)$ is London
penetration depth. For higher velocities, $v>v_c(T)$, the interaction energy of
two vortices situated along the velocity direction is enhanced and along the
perpendicular direction is suppressed compared to the static case.
