Not sure what park you are thinking of, but last year we were at Epcot on Christmas Eve day and it didnt seem too bad at all. We started in the Land making cookies at 12:30, then spent the rest of the afternoon touring WS, checking out the "Santas" and the kids made masks. We went to Le Cellier(with CP package) and then to CP, and finished off a few more countries. The crowd level there then was nothing compared to MK on christmas and the following days.