The relaxation dynamics of optically excited electrons in free Ni₃ has been investigated. By means of femtosecond two-color pump-probe photoelectron spectroscopy the relaxation of excited electrons via inelastic electron-electron-scattering could be observed in read-time. The unexpected short electron-electron-scattering time of 190 fs is caused by the relatively large density of states in the vicinity of the highest occupied cluster orbital. This large density of states is results from the narrow bandwidth of the partially filled d-levels in the transition metal clusters. Other aspects for the enhancement of inelastic electron-electron scattering are the spread of the electronic levels by vibrational broadening and the spill-out of the s/p-electron wave functions intensifying the Coulombinteraction between the electrons.