The Windjammer can be a madhouse at certain times. Embarkation day, debarkation morning, and the mornings when you are arriving in a port.
Not much you can do about the embarkation day lunch crowd other than get aboard early and hope to be among the first to get to the buffet (like we did last year on the Liberty Of The Seas). As for the other peak crowd times - go to the dining room and all your troubles will fade away.
Otherwise, I've never felt these ships were crowded and I've sailed with maximum passenger loads on both the Freedom and Liberty.