It's going to be a combination of both, as the runway that is currently closed for construction allows for two runway operation in the prevailing severe wind conditions. Yes there are delays but not as bad as when it's down to one runway. I think yesterday was the worst, averaging over 4 hours with ground holds as well.

And yes all airlines are affected, it just depends on how the delays are dealt with. AA is cancelling flights from the smaller airports, DL is basically delaying some flights to keep others on time.