Three years ago I would have said, yes, that you would definitely find times where DLR was less busy. However, since the 50th, DLR marketing has done an incredible job keeping the parks' attendance high year round.
I have never been to WDW, but I have heard others mention the fact that since DL is smaller than the Magic Kingdom at WDW, that DL often times seems more crowded because of its narrow walkways and smaller layout.
DLR is a locals' park and a large amount of its attendees are AP holders. So you will find the parks more croweded on weekends and even weekday evenings.
Like Hound said above, you will find lower crowds mid-week year round (with the exception of Spring Break, week between Christmas/NY and President's Day week).