That's right 840, most Cork-US passengers travel via London and Amsterdam.
Thing is to attract a carrier on a Cork-US route (not that it's going to happen this year or next!) with a 7,000 ft runway, the carrier will have to have a 737-900/757/787 so it won't be weight restricted. Kind of limits your chances of attracting a carrier in the first place.
It's more than 20 years since the runway at Cork recieved it's last modest extension, it's high time it recieved another. A 7,000 ft runway is quite short by international standards.
By the way, I read that there will be a feasability study done this year on extending the 17/35 runway in Cork. You can read it under "Development Plans" on the link below
Cork Airport - Wikipedia, the free encyclopedia