Last night it was a combination of a late inbound aircraft and snow in Amsterdam leading to the aircraft needing to be de-iced before it left for Cork.
To be honest, the greatest cause of the delay is the boarding procedure in Amsterdam where passengers go through security at the gate.
This was changed a few years ago. Essentially because Ireland is non-Schengen, Cork-bound passengers can mingle with passengers who have arrived off non-EU flights. This means they have to be screened at the gate. For Schengen countries, more normal boarding procedures of a single security check at the entrance to the airside area apply.