Maxalt & LuZuck:
Point taken ;-) Of course I never take off with loads of wet snow or ice/rime on the wings. What I had in mind was the other day when it was around 14-15 below freezing and the snow was very dry / loose. The wind was about 11-13kt, so the only precipitation sticking to the aircraft was that which hit the heated windshield and melted. If we'd applied a layer of sticky fluid to the airfoil; wouldn't this reduce Clmax more than if we let the snow blow off? (Our SOP requires all V-speeds to be raised by 10kt when de-/anti-icing is performed). If there is any doubt, I always insist on deicing, but in this particular case, both the captain and ground personnel inspected the wings and we decided to go without deicing.
Anyways, I must admit I never really thought traces of rime could f**** up the a/c performance that bad (as Maxalt describes), but from now on, this F/O will start deicing a lot more often.
Merry Xmas airmen!