Originally Posted by
corporate-wage-slave
OK, I wasn't being clear. As you go up the escalators to Security, the first two lanes are for Fast Track Connecting Passengers. The next 4 to 8 or so lanes are also for Connecting Passengers, and the last ones tend to have the shortest lanes.
Absolutely agree with this. Fast Track is useful for getting to the security lanes more quickly. Once you go up the escalator, pick the shortest line you can!
Security is definitely a function of what time in the day you are traveling. It tends to be much worse in the morning although I don't think the OP should lose sleep over it. I once connected through LHR on a weekday in July around 17:00 and there was practically no one at security.