It takes some more time, but not as much as you may think. It also isn't that extenisve as at the airport. You just have to walk quickly through a detector and let check your bags - the stuff often isn't really interested at what is in your bag. But we never where at the subway during the real rushhour - no idea how this works out when so much people need to go to the Subway!

We were in China for three weeks and came back mid August.