The security problems are intermittent. Some days, even when it's busy, the queues are fine. The new security hall seems to have the capacity but is sometimes understaffed compared to demand.
A recent statement from GIP apologised profusely for the problems and said that they are in the process of tackling them. They claim that pax numbers are significantly higher than expected, not because of additional flights, which they had planned for, but because load factors are higher than previous years, which they hadn't planned for.
The higher load factors must be good news for the airlines/EDI and are a positive sign for business and tourism but, in fairness to GIP, are not as easy to plan for as extra flights, especially if the higher load factors are the result of late bookings.
The criticism of EDI security problems in this and other forums is certainly warranted and GIP needs to better match security capacity to demand. It's not in GIP's interests to have these security delays as it reduces the time that pax can spend in the shops and food/drink outlets, it inconveniences pax and it inconveniences airlines. All of these are bad for business.