If terrorism is no laughing matter, somehow Jonathan Karp never got the memo. His book and lyrics for How to Save the World and Find True Love in 90 Minutes, which just opened at New World Stages, think nothing about making light of bio-terrorism, the United Nations, and (of course) love. Unfortunately, they don't think about much of anything else, either.

Despite referencing everything from melon fights and yoga sessions to psychotherapy, mind-reading, and more, this is a strenuously empty show that makes only its overexpenditure of effort seem effortless. Even its version of a built-in starmaking part is more a forced marathon than an ornate display case: Michael McEachran must work so hard that he barely has time to leave the stage, let alone breathe while he's on it.

Let's pause to give credit where it's due. McEachran is a human perpetual-motion machine, to be sure: As both the show's hero (Miles Muldoon) and its villain (the enigmatic He), he's practically always running, dancing, quick-changing (clothes or the set), or enacting pratfalls absurd enough to elicit double-takes from the Three Stooges. With a shock of bright red hair crowning his tall, unevenly lumpy frame, he's got the perfect Hanna-Barbera for the roles at the center of this cartoony world of international intrigue.

So what if, as the evening progresses, his voice starts to falter regularly and he's constantly out of breath? The greatest of animated heroes are fallible, and McEachran's mortal endurance pales next to the Olympian's stamina he displays anyway. His constantly teetering on the brink of disaster is a big part of the fun, and you're pretty sure he'll always make it through and come up doing a comedic one-man fist fight.

Unfortunately, even McEachran's energy is insufficient to light the theater given the black hole that Karp's book and lyrics conjure. While they're not bad (except for a distressingly casual sense of rhyme), they are overly obvious, and provide neither compelling character content nor a satisfying outlet for the frenzy they painstakingly provoke. U.N. bookstore clerk Miles being caught in a love triangle with coworker Julie (Anika Larsen) and sexy diplomat Violet (Nicole Ruth Snelson), whose activist boyfriend (He) is plotting to take down the U.N., is small potatoes in the grand musical scheme of things.

It hasn't always seemed so. When I first saw How to Save the World... at the 2004 Fringe Festival, it had a sense of importance about it - however overexaggerated - that provided a stronger comic context for the show's events. Juxtaposed against intentionally parodic and minimalistic direction, what it lacked almost completely in substance it significantly compensated for in laugh-getting verve.

Now, in this more elaborate production, with the newly added (and oddly labored) direction and choreography of Christopher Gattelli, the show feels less guilty-pleasure frivolous than head-scratchingly vapid. Even the show's most basic plot point, that Miles develops the ability to hear others' thoughts after he's beaned with a watermelon, feels like a stretch that will cause your already taxed suspension of disbelief to snap.

That this leads primarily to predictable one-liners and crude sex gags is almost beside the point: The fantasy now seems just too concentrated to accept. That's a risk taken by all Fringe transfers, as what works downtown at modest ticket prices won't always play in a legit venue requiring more money to get in. But most shows don't change in spirit this much while changing in material this little.

The show is essentially identical, with all the previous problems remaining. These are perhaps most notable in the score, whose crunchingly conventional music is by Seth Weinstein, which seems as disconnected from reality and consistency as the plot. Larsen, one of Off-Broadway's most dynamic belters, gets little more than a lame Celine Dion parody to strut her considerable stuff; Miles's first big song involves rattling off the names of U.N. member nations at an unnecessarily high speed, a la Ira Gershwin's "Tschaikowsky" without the danger element; and Snelson's raunchy showstopper "Violet's Confession" is more unsettling than erotic, given its subject of partisan violence being a major sexual turn-on.

Snelson is wonderful doing it, but it gives her and here character nowhere to go, and is but a tiny island of questionable excitement in the show's otherwise stormy seas. Larsen has it even worse: Her role requires her to be Miles's secret romantic ideal, but allows her no opportunities equal to Snelson's to win our love. The best material almost invariably goes to a Hellenic chorus, consisting of Stephen Bienskie, Natalie Joy Johnson, and Kevin Smith Kirkwood, that plays dozens of supporting roles that make for nimbler, less-self-conscious fun than is otherwise de rigueur.

The set, by Beowulf Boritt, is a semicircular, multi-doored affair that visually merges the show's Greek and farcical leanings. It's hard to imagine a better metaphor for How to Save the World...: When hubris and slapstick intermingle, the results are guaranteed to be explosively erratic. But the real tragedy here is the talent onstage being squandered in a show and production too busy being mindless to see its performers - and audience - being run ragged.

How to Save the World and Find True Love in 90 Minutes
New World Stages / Stage 5, 340 West 50th Street Between 8th and 9th Avenues
Tickets online and current Performance Schedule: Telecharge