I think like all airports it depends on what time you go through. I recently flew out mid afternoon on a Saturday, arrived at security at 12.30 and what through in less than 10 minutes. But I've also faced long queues, early morning is the worst but nothing different to what I've experienced at MAN, LBA and EMA at similar times
Agreed the building work, although much needed is not going to be great and yes, Sunday late morning will be a nightmare with a 380 and 2 X 787 on the decks at the same time.