Queues stretching for miles have created frustration among travellers and temporarily blocked an ambulance.
Around 17,000 people travelled through the Port of Dover on Saturday morning on their way to France, with ferry passengers waiting hours to get through traffic at the border.
Officials warned people they would have to wait for up to two hours upon arrival at the port to clear passport control, run by the French Police Aux Frontieres.
Traffic snarled along the A20 towards Folkestone for about five miles, with jams extending into the town and temporarily blocking an ambulance flashing blue lights.
Overnight, officials told travellers not to arrive more than three hours before their sail time.
Some drivers vented their frustration by honking their horns, with port officials saying shortly before 11am there was a 150-minute wait.
This had come down to 45 minutes by 2pm, with officials writing on Twitter: “The border processing time from arrival at the Port is 45 minutes with traffic flowing well – we thank you for your patience during a busy morning for summer travel.”
They are encouraging travellers to have their tickets and passports ready to speed up the process and have set out animal welfare points ahead of the border controls, with water refill points positioned beyond.
One woman wrote on Twitter that she waited 45 minutes and there was “good queue management” in a “marked improvement on the chaos this time last year”.
More than 35,000 people made the crossing on Friday on what is likely to be one of the busiest weekends of the year as thousands set off on their summer holidays.
French police said it has mobilised all of its border control staff and they are sleeping in hotels on British soil to avoid any gaps in shifts.
They also said there are seven lines for coaches instead of four and there is an increased potential of 11 lines for light vehicles, with a “buffer” car park capable of holding 70 coaches for those arriving in advance.