Good question, but if I remember correctly, the cold in the future pork warehouse - the only occasion when he was really, really intelligent and quick thinking, was so cold it almost killed his fellow colleague. So it seems to have been somewhat chillier than the winter in bonk; also, the cooling helmet still seems to be around, or at least I always presumed it was, so his intelligence level was more or less always the same except under very extreme conditions.
Still, I can't really answer that question, either.