We were there from 5-14 to 5-21 and I could not believe how heavy the crowds were.
I guess crowds are in the eye of the beholder. We were there at the same time (left on the 21st and didn't go to the parks) and found the crowds to be unbelievably light with the exception of the EMH nights, which were a disaster. Other than that, we didn't wait in a line that was more than 10 minutes. In fact, we walked on to Mission:Space, Soarin', and Rock N Roller Coaster, among others. We couldn't have been happier with the crowds.