“The Marriage of Figaro” may not be music’s best opera, or even Mozart’s best opera. But this much is clear: It is the most felicitous three-and-a-half hours of music ever penned. If a work that ambitious and involved can be perfect, “Figaro” is.

And the Salzburg Festival has a new production, fashioned by a young German, Claus Guth. It is an interesting production, but stylized, stagy, saying, “Look at me!” Some of us prefer to see through a production, to the story at hand.

One of Mr. Guth’s innovations — if that’s the word — is a cherub, who appears throughout the opera. Or you could call him a Cupid, or an Amor. An unenamored friend of mine called him “that feathered thing.” This thing is not a cute little boy either, toddling around in a diaper — it’s a man in his late 20s. He interacts with the characters, at virtually every turn. For example, he struggles with the Count like a professional wrestler. And, as Susanna sings “Deh vieni, non tardar,” he makes out with her.

This “Figaro” has many other “innovations”: Susanna very clearly returns the Count’s amorous interest. And the Countess actually gives the ardent Cherubino what he wants (well, some of what he wants). Susanna goes at him too — she’s a very active maid in this production. Mr. Guth’s conception is grossly oversexualized, as is typical in our time, and particularly on this continent. Mozart is sexual enough without overdoing it. Everything in Mr. Guth’s production is so aggressive, so blatant; a little subtlety would be much more in keeping with the score, the libretto — everything.

Last, I will tell you that Mr. Guth peppers the stage with a few dead birds. How come? I don’t know — I guess because he’s the director and you’re not, bucko.

Sunday afternoon’s performance, like all performances of “Figaro” this season, took place in the Festival’s new House for Mozart (which is the former Little Festival Hall, refurbished). And the performance was led by Nikolaus Harnoncourt, the veteran Austrian conductor. He made some peculiar choices: Tempos tended to be very slow, and this was particularly true of the overture, which bordered on ponderous.Also, the ending of “Non so più” was painfully dragged out, and “Porgi, amor” was too slow altogether (as it often is). Other tempos were unconventionally fast.

But Mr. Harnoncourt, an intelligent musician, had reasons for what he did — and he demonstrated some marvelous conducting. He brought out the explosiveness and volatility of the score. And you should have heard the martial majesty at the end of “Non più andrai.” The opening pages of Act IV — in that rather creepy F minor — were amazingly tender, poignant, and lyrical. And the opera ended with Mozart’s special D-major electricity. I have never heard Mr. Harnoncourt conduct better, in many, many outings. Whether you agreed with him or not, he was authoritative all through.

The cast was stocked with top-rate singers, but I will first mention Anna Netrebko, the Russian soprano, for she is clearly the star of the summer. She is almost a rock-star opera star.As Susanna, she acted superbly, being an excellent flirt, for one thing. To borrow an old line, you couldn’t take your eyes off her. But her singing was inconsistent. She was frequently sharp, especially in the early going; and she is always a bit cold, vocally, for Mozart. But she does many things well, including recitative. That’s a good thing, because Susanna has a boatload of them.

In the role of Cherubino — a trouser role, as you know — was a soprano, instead of the usual mezzo.This was Christine Schäfer, the astonishing German. With her pixie-ish frame, she looked very boy-like indeed. And she boasts what a musician friend of mine proclaims “the best boy walk in opera.” As for her singing, it was consummate, as you would have expected. “Voi che sapete” was a little Romantic, but convincing. This is a woman who can do whatever she wants, with her technique, and her musical smarts are considerable.

Our Figaro was Ildebrando D’Arcangelo, the Italian bass-baritone. Chief among his possessions is a splendid instrument: rich and regal.What was lacking on Sunday afternoon was a little suppleness, a little bend. For example, the aria “Aprite un po’ quegli’occhi” had no Mozartean bounce, only royalsounding anger. Our Count was Bo Skovhus, the Danish baritone, who still looks like a million bucks. He sang like about 500 grand (which is darned good). I can’t remember whether Mr. Skovhus ever had low notes; if he still has them, they deserted him in this performance.

You had to pity Juliane Banse, a second German soprano, for only this reason: She took over the part of the Countess from Dorothea Röschmann, still another German soprano, and one of the best Mozart singers in the world. Ms. Banse is a fine singer herself, although her sound on this occasion wasn’t real clean — there was a fuzz on it. And on the subject of German sopranos: A fourth, young Eva Liebau, portrayed Barbarina.Watch for her in larger roles, in coming years. (Lots of lyric sopranos have started as Barbarina!)

Finally, a word about the cherub, or the Cupid, or the Amor — that feathered thing. He was enacted by Uli Kirsch, whose bio describes him as a juggler, acrobat, and so on. You will want to know that he was “repeatedly declared world champion of the unicycle.” And he rode that vehicle onstage, weaving around the singers, at one point going backward. Yeah, that was impressive.

Salzburg Festival until August 31 (for more information, call +43-662-8045-500).