I know, i have all my HDRIs saved in 3 resolutions: original, medium and small. I always pick medium rez one for scene building and testing and i almost always forget to swap it with higher rez when rendering finals :] Shame on me.
@Dionysios.TS, no problem, i like to share knowledge :] Actually, this metal material looks pretty meh in bright light conditions, but since i intentionally lowered enviromental light intensity, metal became much richer, more contrasty and started to look better.