A high performance circuit breaker wherein an electric current flows through the first (22) and second (32) contact carrying support. The terminal (24) is crossed by electric current (I1) in a set orientation, whereas the arms (28) are crossed by electric current (I2) having a substantially opposed orientation in an essentially parallel direction, with respect to current (h). The interaction between the currents (I1 2) generate a repulsive electromagnetic force F which is able to distance the arms from the terminal, creating additional contact pressure between the contacts. Even though the second contact carrying support is crossed by electric current (b) having a substantially opposed orientation in an essentially parallel direction with respect to current (I2), generation of a further electromagnetic force, which would tend to separate the arms from the second contact carrying support, unwanted electromagnetic repulsion between the contacts is avoided by the first (50) and second (70) ferromagnetic shield.