Emma Seligman’s Shiva Baby only runs 77 minutes, but it feels like an eternity. This is a compliment, I promise. Seligman’s film is like a bottle episode version of a slacker comedy, with her self-sabotaging antiheroine Danielle (Rachel Sennott) stuck at a shiva that feels like the stuff of nightmares. Seligman takes us on a busted roller coaster of emotions and embarrassment, perpetually getting stuck on the uphill climb before finally crashing down with whiplash-inducing intensity. Shiva Baby is very funny, but it may also give you muscle cramps from cringing.

Sennott’s Danielle is an aimless college student living in New York on her parents’ dime. She makes extra money from a regular rotation of sugar daddies, the first of whom, Max (Danny Deferrari), we see in the movie’s opening moments. Post-hookup, Danielle rushes over to meet her parents, Debbie and Joel (Polly Draper and Fred Melamed), at a shiva for a distant family friend. There, she encounters nosy, cheek-pinching relatives who, along with her mom and dad, keep trying to get her job interviews. Danielle’s ex, Maya (Molly Gordon), is also there making things awkward. On top of everything else, Max shows up, too, along with his gorgeous wife Kim (Dianna Agron) and their screaming infant daughter.

Shiva Baby is an exercise in comic tension, and Seligman does a good job of letting the anxiety build, bit by bit. Each of Danielle’s major relationships experiences its own conflict and arc within the space of house where the shiva is taking place. Sennott bounces well off of Gordon’s Maya, who’s considerably more together than she is, and everyone knows it. There’s also a good push-pull with her mom, Debbie, and Danielle’s anxiety that Debbie thinks she’s a total burnout.

Because of the claustrophobic setting, the awkward encounters Danielle (or any of us) would normally try to avoid are completely inescapable. They’re also happening all at once, and Seligman expresses the sensory overload of that feeling through frequent closeups and a sound design that’s so crowded it sometimes feels hard to breathe. Like at a family function, we’re constantly running into the same folks over and over again, the same aunts and cousins tutting that Danielle isn’t eating enough, the same guilty glances from Max and withering stares from Maya. After all, there are only so many places we can go.

It also helps that many of these performances feel believable. Melamed plays a classic dad, frequently losing his phone and getting adorably excited over the dessert table. Draper balances her overbearing mom-ness with genuine love and concern for her daughter. If anything, it’s a little disappointing we don’t get to see more of that relationship. As Danielle, Sennot is a believable early twentysomething, masking the terror she feels about adulthood under a veneer of street smarts, sarcasm and selfish choices.

Shiva Baby is a feature-length version of an existing short film, and it’s easy to see how the film’s appeal would work better in a shorter format. In its longer form, it sometimes feels like the ebb and flow of anxiety is the only trick the film has up its sleeve. It’s effective, but starts to feel a little too cyclical after a while. Still, Seligman squeezes a lot of relatable comedy and character out of a simple premise, and it winds up being a brilliantly economical decision.