We present angle-resolved photoemission experiments on 1T-TiSe2 at temperatures ranging from 13K to 288K. The data evidence a dramatic renormalization of the conduction band below 100K, whose origin can be related to the new potential responsible for the charge density wave phase at low temperature in this system. The renormalization translates into a substantial effective mass reduction of the dominant charge carriers and this observation is thus in opposition to the common belief that strong interactions produce heavier quasiparticles through an increased effective mass.