Paxboy
You obviously do not even remotely understand Eurocontrol. If pax are on board with the doors closed the crew are only waiting for one thing.......ATC clearance. You have to board pax on time in case the slot changes at short notice. If this happens it's pointless having the pax in the terminal and 15 mins to a new departure slot. Missing that new slot could result in even more delays than originally anticipated.
What on earth is a fixed slot?