They could put a temporary ban on hand luggage to help the situation at security. Or if they allow one bag, just the person with the bag goes through that part and the other members go through a no bag screening system which might free up some space at least.
I flew last year in the summer , easyJet to Newquay from T1, just as things were getting a bit busier.
I had no hold or hand luggage, so security should have been a breeze, but it was slow even then.
as far as I could see, the issue was hand luggage that was scanned and was found to contain something dubious - eg liquids etc. Presumably because people hadn’t flown for a year and had forgotten about liquid limits and the ability to read the numerous signs…
the issue was then compounded by the dubious trays being pushed into the ‘manual checking’ conveyor belt, but because there were so many of them, that conveyor belt was full, which then meant that no more dubious trays could be pushed onto it, so ALL trays were halted due to that log jam. Which then meant that no body was passing through the scanners and the queue increased Rapidly and exponentially.
so, the issue could be said to be lack of staff manually checking dubious trays, but there is only so much physical space in T1 security, so they can’t overload the manual checking area, nor increase the length of the dubious tray conveyor, nor the holding area for passengers with dubious trays.
how to fix… well, adding no luggage passengers to the fast track would be an idea, just to ensure ‘easy’ throughput is maintained - but that is a very very small amount of people.
Maybe…sending trays through, and only if non dubious, allowing the person to be scanned, might be an option. Any dubious trays are marked and brought back around the scanner and offered to the passenger to sort out their stuff correctly… if it goes through again with issues, they join the very slow queue of manual checks.
longterm - cut down the size of duty free area and lengthen security so there’s space to stack dubious trays and their related passengers, to be dealt with.
edit: when throughput grinds to a halt due to a pinch point - the quantity of dubious trays blocking ALL tray’s progressing, then it’s not down to staffing issues (there isn’t enough space to deal with the dubious trays and also stack up their owners) imho, but maybe it’s something different this year causing issues? But it’s definitely the lack of ‘space’ that has an knock-on possibly unexpected effect