In
The Return of Ultra Woman, I presented a theory that many of Superman's powers - including super speed - are based on a Higgs field manipulation effect that neutralizes the mass of Clark and everything near him. If his biofield creates a small zone of massless air around him, then it should allow him to move through it and have the air pass around him in a perfect laminar flow. No compression => No shock wave.
I actually wrote a micro-short story, set in my LnC universe, where Bernie explains this to Clark, but right now I don't have enough story to make it viable. Maybe some day that lecture will see the light of day as part of a larger work.
Edit: Credit where credit is due. My ideas about the potential for mass reduction and neutralization were inspired by the
Lensman books by EE Smith Bob
