SF efficiency as a function of the velocity dispersion, shown for clumps (left) and regions (right) in our sample. Clumps exhibit a flat relation, while regions show a weak anti-correlation with increasing velocity dispersion. Considering the full sample, the scatter is large. Colours indicate the merger stage of the galaxies: isolated (blue), pairs (red), early-stage mergers (orange), mid-stage mergers (magenta), and late-stage mergers (black).