One of the worst that I keep unfortunately encountering is PFO especially on a Wednesday or Sunday night the airport and ground agents just can't cope with passenger numbers.
Frequently ex UK you get your slots changed and delayed on this route as they know they have earlier delays, only last week it was so busy we were kept in a hold over Akrotiri air base for 20 mins as no spare stands to park on.
Once on the ground it's just as chaotic you never know if you are going to have a standard turnaround or a 2hour wait. sometimes they will bus one load of pax out to the aircraft then use the bus for inbound flights so taking 1 hour to board and am told when this happens people then wander off from the gate.