From memory, there was recruitment of additional staff and no doubt a fair bit of staff systems and process training/rejiggery to get it working as intended - with sufficient lines operating.
That seems to have worked extremely well. They're confident enough to put a live security queue time ticker on their website. It feels cramped and lacking in natural light - but that is a vibe - in reality, it processes people very quickly.
There's no doubt they're milking the retail strategy and need to press on with terminal expansion but in reality, it is for most people still quite a quick and not at all unpleasant airport to use.