I replaced the Big Apples on my Helios P8 with some Marathon Racers and I think the Marathons are a faster tire but I would expect a much higher psi narrower tire to be faster. It is a much harsher ride than the Big Apples so I guess it is all what your priority is.
I have the Stelvios on my Bike Friday Pocket Pilot and they are very fast. Much faster than the Kenda Kwest's that came on the bike.
Kenal0