Billie Eilish at Electric Picnic 2023: 'I have a fat fever. I'm sick as balls ...

Billie Eilish: she has wrestled publicly with the toll of fame, and that is the subject of many of the songs she performed as midnight loomed at Electric Picnic. Photograph: Matthew Baker/Getty

Electric Picnic had never seen anything quite like Billie Eilish when pop’s grungiest newcomer headlined the festival in 2019. She drew the largest main-stage crowd at that point in the event’s history – and reduced more than a few to sobs of pure emotion.

Four years later Electric Picnic is larger – its capacity now stands at 70,000 – and the 21-year-old is one of the world’s biggest pop stars. She has wrestled publicly with the toll of fame, and that is the subject of many of the songs she performs as midnight looms at Ireland’s biggest multiday music event.

She starts, however, with the early hit Bury a Friend. A sort of art-house horror movie distilled into 3½ minutes of pop, it is grippingly dark and accompanied by throbbing red lighting and flames that make it feel as if Stradbally is descending into a hellish otherworld.

That spiral to hell is paved with heavenly grooves. The slowcore throb of I Didn’t Change My Number finds Eilish holding forth on the burdens of achieving global fame in her teens. (“I didn’t change my number/I only changed who I believe in,” she croons ominously.)

Billie has bad news, however: she is ill. “I have a fat fever,” she explains. “I’m sick as balls. I need you guys to give me all you got.” Eilish’s audience brings its own frenetic energy, however, and her concert lands somewhere between a big pop show and a punk gig, not least because of Eilish’s combative emo energy even as she battles that bug, her eyes teetering on bloodshot.

A mash-up of Oxytocin and Copycat surfs spiky dance beats. Later, her Barbie soundtrack cut What Was I Made For? brings the spirit of Barbenheimer to Laois. This is followed by an acoustic section in which Eilish and her brother and collaborator, Finneas O’Connell, navigate the bittersweet I Love You, a valentine with poison in its veins.

She hurtles towards the finish line with the epically crestfallen When the Party’s Over and Everything I Wanted, dedicated to Finneas and followed by the observation that she’s “Irish – everyone here looks like me”.

Confetti swirls and fireworks light up the sky above the stage as Eilish closes with the red-eyed bopper Bad Guy and a giggle- and cough-strewn Happier Than Ever. The set isn’t as seismic as her 2019 turn. Back then it felt as if you were watching a newly formed pop comet hurtle past. But she’s a fantastic headliner, flu or not. The rest of Electric Picnic will have its work cut out matching the thrills and chills she delivers on opening night.

Ed Power, a contributor to The Irish Times, writes about television and other cultural topics