  We investigate the intensity enhancement and the duration of starburst
episodes, triggered by major galaxy interactions and mergers. To this aim, we
analyze two large statistical datasets of numerical simulations. These have
been obtained using two independent and different numerical techniques to model
baryonic and dark matter evolution, that are extensively compared for the first
time. One is a Tree-SPH code, the other one is a grid-based N-body
sticky-particles code. We show that, at low redshift, galaxy interactions and
mergers in general trigger only moderate star formation enhancements. Strong
starbursts where the star formation rate is increased by a factor larger than 5
are rare and found only in about 15% of major galaxy interactions and mergers.
Merger-driven starbursts are also rather short-lived, with a typical duration
of the activity of a few 10^8 yr. These conclusions are found to be robust,
independent from the numerical techniques and star formation models. At higher
redshifts where galaxies contain more gas, gas inflow-induced starbursts are
neither stronger neither longer than their local counterparts. In turn, the
formation of massive gas clumps, results of local Jeans instability that can
occur spontaneously in gas-rich disks or be indirectly favored by galaxy
interactions, could play a more important role in determining the duration and
intensity of star formation episodes.
