The main difference is that pre-2021 UK travellers simply had to show travel documents whereas now they have to get them stamped.
On the surface, it isn't clear to me why that makes much of a difference in service time, but the CEO of Eurostar pointed a finger to these changes in January: https://www.bbc.com/news/business-64390979, claiming their trains carry 30% fewer passengers due to station bottlenecks.
And yes, they claim the EES checks should help speed this bottleneck.
The main difference is that pre-2021 UK travellers simply had to show travel documents whereas now they have to get them stamped.
On the surface, it isn't clear to me why that makes much of a difference in service time, but the CEO of Eurostar pointed a finger to these changes in January: https://www.bbc.com/news/business-64390979, claiming their trains carry 30% fewer passengers due to station bottlenecks.
And yes, they claim the EES checks should help speed this bottleneck.