When are you going? I think it depends on the season and the weather. We were there in August and late afternoon and early evening were very busy. We went mid day (hot, but less crowded) or maybe 7PM and it wasn't too bad. I remember in October a few years ago it was busier during the day since the weather was better at that time.
You can call and ask them. They have a pretty good idea on busy periods vs. best time for short waits.