As we generally seem to be addressing the (excessive) speed in the first movement, and, with Jarvi, the very beginning, I have ask whether someone knows some programmatic detail that I don't. Just going by the track listings on the CDs I have, "Part One" (which contains the first two movements) is titled "Liebesgluck." That is variously translated as "Love's Bliss," "Love's Happiness," or "Joy of Love." The Chandos notes indicate that there are bits in the allegro that "hint at future events," but I should think that the very beginning of the movement should be giddy, intoxicating, transcendentally serene, or something like that.