When I cleared T2 immigration back in January, the queuing system was woefully inadequate. For UK+EEA arrivals, it was one long queue that then deposits you at the end of the immigration booths, say around booth 30. There were then 10 booths (not all staffed), all the way up to say booth 40. The trouble is, people would wait for a booth to become free all the way at one end, so they couldn't see down towards booth 40. This meant that any border officer at the higher numbered booths would yell and wave for the next person to come over. Some of them were too short to be seen, so they'd have to exit their booth, and walk around to get the attention of the next person; then that person would trudge slowly all the way down to them. I observed that this easily added 30 seconds, sometimes up to a minute (in the case of the officer who had to exit their booth each time) for the person to walk over and be processed. I can't recall exactly the average processing time, but even if it takes a minute to process (which is approx. how long I think it took for me), this means that utilization of the system can be as bad as 50% of the capacity. The solution would be for the long immigration queue to dump everyone into short 2 - 3 person buffers in front of each booth, and for some of the ushers to make sure the buffers are kept full. Anyone with a brain could see this – I don't understand how nobody was doing anything about it.