FWIW I was in DUB last week on an EI flight to JFK. Around 1pm, fast track security only took 5 mins, preclearance with GE as a US citizen only took 2 mins. However, the 51st and green lounge was jam-packed, had worse food than any AC I’ve been to in recent memory, dirty and way too small bathrooms, and limits J pax to only 2 complimentary drinks from the bar. So I def wouldn’t arrive early for that lounge. The good (or bad) news is that it seems Dublin airport realized the lounge is quite subpar and will be shutting it down come October for an overhaul but won’t be opening it back up until 2026, meaning, as of October, no preclearance lounge until next year.