“Zaide,” which premiered on Wednesday evening at the Rose Theater as part of the Mostly Mozart Festival, is an opera so rare it contains no less than three defunct genres. It is not only a singspiel but also a “rescue opera,” and it contains a scene classified as a melodrama. And if these vestigial forms are not enough to guarantee its obscurity, the work was abandoned by Mozart and never even finished during his lifetime. Although there is absolutely no truth to the rumor that Mozart abandoned “Zaide” because he kept falling asleep during its composition, this current production and performance did little to make a case to the contrary.

Most opera fans are familiar with the singspiel form, the most famous example of which is Beethoven’s “Fidelio.” Simply put, it includes alternating musical and theatrical moments. The swashbuckling rescue opera was a form popular in Mozart’s day, and the most familiar now is his “The Abduction” from the “Seraglio,” with a plot and cartoonish villains, features also shared by “Zaide.” These types of thrillers are what modern audiences might consider melodramatic, but the melodrama as a musical genre has little to do with the perils of fair maidens and much more to do with the integration of words and music.

The genre was extremely popular in the 19th century, and in opera today, the melodrama scene probably best recognized by the general public is the Wolf Glen section of “Der Freischüetz” by Carl Maria von Weber, in which the forging of the magic bullets is a spoken affair with incredibly exciting accompanying music.

In the case of “Zaide,”reconstructions of the piece — most notably by the Italian composer Luciano Berio — exist, but Wednesday’s performance offered only Mozart’s fragments without dialogue. The major gaps were at least partially filled by inserting bleeding chunks from Wolfgang’s “Thamos, King of Egypt.”

This would have been a viable methodology for presentation except for one exceptionally wrongheaded decision. Maestro Louis Langree stopped the orchestra each time the work called for spoken lines.These pauses were not short, or even caesuras, but rather fullblown grand pauses, the sort that might occur once in a romantic symphony. Three or four minutes of music followed by 30 to 45 seconds of silence at first seemed curious; after a while, it was just plain irritating. A fellow critic approached me during intermission and asked plaintively, “The second act is not as long as the first, is it?”

This emphasis on negative space severely tarnished an otherwise splendid instrumental effort by the members of Concerto Köln, a period instrument band complete with woodwinds actually made of wood, horns with no valves and flutists who stood while performing. Mr. Langree had them accenting at their most precise, producing a very fine and raucous sound that filled the small hall with an exotic sonority. If only he had allowed them to play through once in a while.

Vocally, this realization was all over the map. Hyunah Yu was a very weak Zaide who would have been virtually inaudible in a normal-sized house. Ms. Yu was by turns pallid and shrill, her cries of despair causing pain that had nothing to do with our empathy for her character. The only aria occasionally excerpted from the score, “Ruhe sanft, mein holdes Leben,” sounded rather wooden.

The men were better. Tenor Norman Shankle was a bit underpowered but displayed the breath control of a budding heldentenor. Bass-baritone Russell Thomas was superb in the melodrama, his stentorian speaking voice mighty and supple.And bass Alfred Walker simply blew everyone else off of the stage in the limited role of Allazim.

George Tsypin built the multilevel set at the very lip of the stage, so people in the front rows had to crane their necks throughout. Those of us in the better orchestra seats had to deal with the bare lightbulb effects of James F. Ingalls, which produced a harsh corona around the faces of the upstairs cast members. Finally, the mise en scene of director Peter Sellars did little to enhance our enjoyment. Setting the action in a contemporary urban sweatshop in order to make a rather ponderous point about slavery — he’s against it — might have seemed more creative had we not already had “Cosi fan tutte” in a diner and “Don Giovanni” in the South Bronx.

Until August 12 (Lincoln Center, 212-721-6500).