  We report on the time-resolved investigation of current- and field-induced
domain wall motion in perpendicularly magnetized microwires exhibiting
asymmetric exchange interaction by means of scanning transmission x-ray
microscopy using a time step of 200 ps. Dynamical domain wall velocities on the
order of 50-100 m s$^{-1}$ were observed. The improvement in the temporal
resolution allowed us to observe the absence of incubation times for the motion
of the domain wall, together with indications for a negligible inertia.
Furthermore, we observed that, for short current and magnetic field pulses, the
magnetic domain walls do not exhibit a tilting during its motion, providing a
mechanism for the fast, tilt-free, motion of magnetic domain walls.
