Speed only matters for the cruise part of the flight. The first and last 45 mins, plus airport time are not different. The slowdown portion of a Mach 2.2 flight will be even longer.

(edit: maybe not much on the slow-down: see Concorde data via link below)

They likely accelerate much faster, and slowing down from mach 2.2 is also fast.

Data from an actual Concorde flight shows slowdown-to-land of around 45 mins, so around the same as a regular flight.

http://www.blodtandsmidigt.com/concordeprofiles.html

Yes, but if the Concorde slows from Mach 2 to 0 over 45 mins then it's average may be ~mach 1. Which is faster than the average velocity of a normal 747.

Granted, if the Concorde shows up and needs to circle the airport for 20 minutes then that's the same delay.

Those data show slowdown to subsonic over the first 10-15 mins of that period.

It also shows fairly linear acceleration to Mach 2 over the first 30 minutes of flight and very rapid deceleration from Mach 2 to Mach 1. Which IMO suggests they could use a different decent profile.

Only in the best case scenario.

One of the reasons Concord "failed" is that it could never fly supersonic over land and had to start slowing long before the destination otherwise it would overshoot (along with fuel costs causing Concord to be more expensive than business class).

Amdahls law