I was actually timing out the QM2/20 super express buses against the regular buses a few days ago on Bustime and it really is amazing how much of a difference the pickups in the beginning make, but also how much better the tunnel to the BQE and Astoria blvd are compared to 59th street bridge down Northern.
It almost makes me wonder why they don't just send Qm2/3/20 down 5th from 57th Street toward the tunnel and just go via the tunnel and BQE. it seems much faster at rush hour.