Effect of primordial mass segregation. Tracking the first 8 Myr (respectively 7.4 Myr after the beginning of gas expulsion) for two 2.5 × 10⁴M_⊙ clusters, without (left) and with (right) primordial mass segregation. Their differences begin to show after stellar evolution produces the first SN, the subsequent mass loss being more destructive for the initially segregated cluster.