If sticky wet snow or precip has melted then refrozen on your blades you have a problem,but the normal hoar frost/light icing associated with overnight parking outside on both main and tail rotors will burn off rapidly at 100% Nr and some pitch is pulled.
I've had to do that on medium Bells where it takes 100% torque to hover with a less than maximum load initially but after a few seconds, performance improves remarkably as the ice burns off.Sounds crazy,I know, but as long as there is no imbalance all blades will clean very rapidly.
Picking up ice in flight is different, especially on the tail rotor which,from my experience, often sheds ice unevenly causing imbalance and serious vibration.Picking up ice in flight on the main blades can appear to have little effect, but the buildup is usually on the slower sections of the blade and affects the autorotative sections.To be avoided obviously,especially in single engined machines.
Aside from the ice building up on rotors,the sheer weight of ice on the fuselage can be surprisingly high.