They were dancing as fast as they could over at Houston Ballet this year. And we mean both onstage and off. Not only did they just wrap up their 40th anniversary season with a fabulously fun La fille mal gardée, but the troupe is also making remarkable headway on the $53 million Center for Dance. The six-story building boasts nine studios for rehearsals and classes, executive offices and a black box theater. When it opens next spring, it will be the largest center in the country devoted just to dance. It's hard to say whether the topping-off ceremony in March was the high point of the season or Artistic Director Stanton Welch's version of Petipa's 19th-century classic La Bayadère. It was pure spectacle, with great dancing — and live snakes. It doesn't get much better than that.