The temporary fast track is both narrow and overcrowded and has passive-roller tray shelves running uphill, so you have to keep pushing your stuff uphill in the boxes for it to reach the scanner instead of rolling away downhill, while also trying to unpack the rest of your stuff.
Work of ... genius.
I frankly think LHR T7 was worse than Stansted last time I went through it, certainly not better, which is quite an achievement. I was even in F, so got to jump most of the security queue and relax in the CCR after struggling across the terminal for a shower and back to the CCR. Horrible place.
It needs an airside T8 to T7 transfer bus.