A lemming falling through an updraft - be it as a faller or a floater (but not a glider, which has a special and intentional rule here) - falls slower than it would if it were not falling through an updraft (1px per frame for a floater, or 2px per frame for a faller).
Ohnoers, on the other hand, continue to fall at normal speed whether in an updraft or not (3px per frame, which is the same as a faller who is not in an updraft).