Airspace does not create delays.
"It's about the Runways (and taxiiways) Stupid"
Perth had to go to taxi slot times because TWR could fire aircraft off one RWY fast enough to 'overfil' the airspace. As soon as it calls DEP an aircraft becomes 3nm long and 3nm wide, radar sectors it's 5nm long/5nm wide, in procederual airspace (160nm PH) it's 20nm long and 28nm wide (GPS) or 10 minutres long and 60nm wide. The fact that 90% of PH traffic is in a 135 degree arc doesn't help.
NB