I'd have to disagree with this. We went in April (the last week) this year. Every park was an absolute madhouse. Granted it might not be "as busy" as it would in say the height of summer or during Christmas, but we were thinking this was a slower time. It didn't turn out to be the case at all. The only relief from the crowds (somewhat) was at UO and SW. I vowed never to go back in April again.
i think it depends on your own perspective of busy! we have been the last 2 years end april begining may, and are going back roughly same time next years. we have thought both times to be fairly quite. i suffer from panic attacks in crowded places and only had 2 problems with it this year. both times it was partly my own fault and could have been prevented.
the 1st one: we watched spectro from outside the chrismas shop in liberty square, then tried to walk across main st to tomorrowland straight after.
2nd one: watched wishes from main st near caseys corner then tried to go to splash mountain.
both times everyone else was leaving the park (we had stayed for emh) so was hard trying to get through crowds.
susan555 try worry bout it being busy now, it'll just make it worse for you. i found it ok.