A polyorganosiloxane composition that can be vulcanized at high temperature to a silicone elastomer, useful in the field of the manufacture of electrical wires or cables having an improved fire performance is provided. The composition includes a semi-reinforcing filler chosen from the group composed of:—calcined kaolin powders, preferably that have undergone a chemical surface treatment;—talc;—calcium carbonate that may or may not have been surface-treated, for example with vinylsilanes, aminosilanes or (reactive or unreactive) silicone oils; and mixtures thereof.