We study the instability of the superconducting state in a mesoscopic
geometry for the low pinning material Mo3Ge characterized by a large
Ginzburg-Landau parameter. We observe that in the current driven switching to
the normal state from a nonlinear region of the Abrikosov flux flow, the mean
critical vortex velocity reaches a limiting maximum velocity as a function of
the applied magnetic field. Based on time dependent Ginzburg-Landau simulations
we argue that the observed behavior is due to the high velocity vortex dynamics
confined on a mesoscopic scale. We build up a general phase diagram which
includes all possible dynamic configurations of Abrikosov lattice in a
mesoscopic superconductor.Comment: 7 pages, 6 figure