"Not so fast!" is what "allegro non troppo" seems to mean but not signify in Italian, and it's an ideal title for a movie - now at the Key - that sets out to parody Walt Disney's "Fantasia" and winds up proving that parody is the sincerest form of imitation.

Italian animator Bruno Bezzetto has taken the original Disney idea of combining cartoon characters with classical music, robbed it of its piety, goosed up the humor with a little more cruelty and a little more sex, and produced a movie as funny and finally as endearing as the old art-movie warhorse he's making affectionate fun of.

Debussy's "Prelude to the Afternoon of a Faun" is the background for a comedy of baffled lust, as an old and paunchy faun chases a series of increasingly voluptuous and inaccessible nymphs.

Ravel's "Bolero" is a story of evolution told to insistent dance music - a simultaneous parody of "2001: A Space Odyssey" and the "Rite of Spring" section of the original "Fantasia." Instead of dinosaurs and volcanos chewing and exploding to the beat, Bozzetto has his animals - big-hipped, falbrumpted, stolid stompers - parading endlessly across the screen looling for the future and winding up only in the apocalyptic present.

Stravinsky's "Firebird" is an anti-morality tale in which a very happy and loving Adam and Eve refuse to eat the apple. So the serpent tries it, and finds himself bedeviled by a group of very cheerful and formidable-looking demons who introduce him to modern life - TV ads, billboards, commercial sex and violence - all in collages of gorgeous color.

Bezzetto seemed less successful with more sentimental material: A wide-eyed cat wanders through its memories of the dilapidated house it used to live in, and Sibelius' "Valse Triste" mourns along in the background. But two short sequences, a doubletime Dvorak "Slavic Dance No. 7" and a deliberately over-cute honeybee who keeps trying to eat a flower in time to a Vvaldi "Concertoi in C," are fast and furious and good fun.

There is also a sort of frame story, which is supposed to be a parody of the original shots of Stokowski and the Philadelphia Orchestra in "Fantasia." The press release called the frame "Fellini-esque." It is, a little - but live people aren't as beautiful or grotesque or funny as cartoon people, and the slapstick seems amateur compared to the animation.

A little warning to parents of small children. "Allegro" may be dangerous - not because it shows some very innocently drawn nudes, but for the same reason "Fantasia" was. Children tend to get the pictures stuck in their minds and see them again whenever they hear the music. I will never forget how shocked I was when I first learned that "Rite for Spring" was music for a ballet that didn't have a single dinosaur or volcano in it. And I still can't stop that stupid devil from unfolding his wings in my mind every time I hear "Night on Bald Mountain." At least play "Bolero" for the kids before you take them - it would be terrible if they grew up convinced that it was designed not for human dancers but for bedraggled monsters doing the mutation stomp.

But take them to see "Allegro" by all means. This is a parody every bit as good as the original.

All "Allegro Non Troppo" really needs is four or five very bad splices that get the music and the animation out of sync, a reel where all the colors have faded, and a big white scratch with technicolor green edges running down the middle of the frame - then it would look exactly like "Fantasia" did the first time (and every other time) I ever saw it.