I am not going to say August is better, but I will say the following:
1. If you avoid the weekends in August then the crowds at DLR are tolerable
2. Late March is Spring Break time, and DLR can be as crowded as in August
3. If you are doing a multi-day trip and staying at a hotel very near DLR that makes it easy to take afternoon breaks, it is much easier to work around the crowds
4. Personally, I like DLR in the summer where you throw on a pair of shorts, a tee-shirt and some sandals or sneakers and are comfortable from first thing in the morning until midnight.
5. When you go in the summer, the maximum number of rides are operating and the maximum number of shows and parades are running
6. The park hours are maxed out in the summer
7. I have been to DLR in off-season when the crowds are extremely small. It was fun to get on so many rides, but it felt very odd. It would be sort of like going to a Broncos football game and having the stadium be empty. Somehow the crowds are part of and enhance the experience. But that is probably just me. In general, I am not a big fan of waiting in lines.