Clark in Smallville is on the phone talking to Chloe in Metropolis. Chloe suggests Clark get over there and *poof* he's there a second later. It's roughly 180 miles between the two cities (a 3-hour drive). That means Clark traveled at 648,000 miles per hour. The speed of sound is 760 miles per hour, so that means Clark was travelling at Mach 852! He's never been demonstrated to be anywhere close to that fast before.