Sometimes you may come across a work of music so beautiful that you wonder why you’ve never seen it performed before. Then you see it performed and understand why.

Clocking in at 70 minutes, Ferruccio Busoni’s piano concerto, which Garrick Ohlsson performs with the NSO this weekend, is a monster. And based on an unscientific survey of friends who attended Thursday’s concert, it elicits the same general reaction: “It’s long;” “His publisher must have paid him per note;” “Could’ve shaved off 30 minutes;” and “It’s really long.” I didn’t poll the two people sitting in front of me who, around the third movement, took out their phones and started checking their Instagram feeds, but I imagine they’d concur.

There are other reasons it’s never become standard orchestral repertoire (the NSO has only done it once before, in 1943): chiefly, the odd inclusion of a male chorus—-which doesn’t do anything until the finale—-creates an additional logistical challenge for orchestras. It’s famously difficult for soloists. There’s also the fact that Busoni wrote a straightforward Romantic piece in the early 20th century, when that stuff was increasingly passé.

Those are also the very things that make Busoni’s concerto so rewarding to see in the hands of a pianist as good as Ohlsson. When I last saw Ohlsson with the NSO in 2010, I was less impressed by his take on Beethoven’s fifth piano concerto, which came off as plodding and heavy handed. But Ohlsson is a heavy-handed pianist, one who over-enunciates as if playing notes one at a time rather than whole phrases, and that same style worked wonders in a heavy piece like Busoni’s (Busoni wasn’t a fan of Beethoven, for whatever that’s worth). At times his hands perch over the keyboard like talons before swooping down for an attack, at others he stabs at the keys with his index fingers, like an old person typing. He’s forceful, efficient, and also prodigiously talented.

For a piece that’s already hard to play, Ohlsson makes the feat more impressive by doing the whole thing from memory, whereas I have difficulty memorizing my Social Security Number. The Washington Men’s Camerata joins in at the very end for an enjoyable if incongruous “Hymn to Allah”—-Busoni wasn’t Muslim, he was just really into Aladdin—-despite sounding thematically out of place, as if Busoni had written it for something else, couldn’t figure out what to do with it, and said “what the hell, I’ll just stick it onto the end of that piano concerto, it’s already an hour long” which is exactly what happened.

It’s too bad, then, that relatively few people were there to see it. Ohlsson should be a big draw, yet the Kennedy Center’s concert hall Thursday was half empty. I’d speculate the first half of the program, Stravinsky’s Firebird suite, scared a few away (probably the same who stayed away from last week’s Stravinsky program). Stravinsky tends to do that, which is perplexing because he’s not that scary: he was in two Disney movies, Fantasia and its sequel. So he’s ok for kids but too weird for adults? This wasn’t even the weird Stravinsky; his Firebird suite (here, the one from 1919) is conventionally pretty, with soothing lullabies and majestic dance movements. Guest conductor Rossen Milanov led the NSO superbly, emphasizing dynamic and tempo contrasts from a restrained opening to those frenzied dances, the strings and horns perfectly synched on the downstrokes in the Infernal Dance. And though the wheels threatened to come off at the very end, it could be the tightest the NSO has been so far this season.

With an unknown entity like Busoni, a lot of people don’t know what they’re missing. Length aside, it’s a gorgeous piece, even more so in the hands of an expert soloist. Its only drawback was Busoni’s overly lofty ambitions. There was enough material in it for two or three piano concertos and a standalone choral work; had he opted for something less grand, Busoni’s legacy might have been something other than the guy who wrote the piano concerto no one ever performs.

The program repeats today, November 21 and Saturday, November 22 at 8:00 pm at the Kennedy Center, 2700 F St. NW. $10 – $85.