It depends a lot who the irish bank is using for their international transfers.
I do some transfers to Germany regulary and I notices strange things when making payments to the same banks:
PTSB, before 1059 in the branch for free - there same day (9 out of 10)
They use citibank and that seams to speed things up.
Halifax, before 1059 via the phone for free - 3 days (5 out of 5)
I assume RBOS in the background
I see similar things when IBAN transfers are done to the UK to an € account
PTSB, before 1059 in the brank for free - there same day (5 out of 6)
Halifax, before 1059 via the phone for free - next day.
So neither PTSB nor Halifax charge for standard transfers but because they use different bankends the transit is diffent.
These are personal experiences and YMMV