Is there even room for another (parallel) runway?
By adding more gates it should help alleviate some delays.
I'm not the biggest expert on how an airport works. Far from it, even though I spend half my time in them.
But when I go to LGA my experience isn't just that I spend a lot of time waiting at the gate. That special form of gehinom which is LGA also entails sitting on a plane for an hour and listening to announcements of, "Don't worry, folks. We're number fifteen."
Bottom line: that would seem to indicate lack of space at the runway.