The artists aren’t just present, they’re relentless. Action Hero’s Slap Talk is more than a dialogue, and more even than a six-hour long dialogue, though its length goes straight to some eyebrows. Reading from an autocue and displayed to their audience live on a monitor while also before them, two people scrap verbally like rival boxers, compelled seemingly without end. The text swells, curls, repeats and references, and only the audience are allowed breaks.

This incredible duration allows Slap Talk to flick through different forms of conflict, always avoiding categorisation into a definitive narrative or explanation. Starting points are taken from a televangelist, from Obama’s speeches, and the language shifts from playground taunts to Apocalypse Now (1979) to something else again and again.

While I’m fond of the godlike assertions of superiority, Gemma Paintin’s personal favourites include the shopping channel and middle-class one-upmanship sections. “That kind of passive-aggressive talk about organic food is the killer for me in real life. It makes me want to scream.”

Based in Bristol since they began making work together in 2005, Action Hero is the company of Paintin and James Stenhouse. What they create is performance at its most ambitious and undiluted: this year, Oh Europa will see them conduct a six-month tour across every country of the EU in a motorhome. They’ll be recording love songs sung acapella by people they meet in an unorthodox archiving, broadcast simultaneously throughout Europe and eventually leading to a larger performance fed by the connections and exchanges fostered by the project. They’ve made westerns in bars with their audience (A Western), navigated the tropes of American teen sports movies (Hoke’s Bluff), and one person at a time has experienced their piece based on the ‘enhanced interrogation’ methods of the American military with an onslaught of immersive multimedia.

This last piece is Extraordinary Rendition, which played at HOME in Manchester alongside Slap Talk. The isolated subject is seated for twelve minutes in an aeroplane seat in a cabin constructed from the same materials as a Camp X-Ray cell, hearing the voice of the attendant in their headphones and given coffee. Three small screens flash up text from pop songs which has been perverted for war films, air traffic communication or torture. It’s a “journey through, rather than a representation of” the territory of warfare and anxiety, Paintin explains, a disquieting look into how the military-entertainment complex overlaps, resembles and makes use of cultural touchstones.

“It’s not scary or spooky, but it is intense for some people. It’s a very solo experience.” While Paintin performs in Extraordinary Rendition, she barely sees the audience, which she acknowledges leaves their reactions mainly private. The audience can leave Slap Talk, but the performance gains much of its violence from its unique form and witnessing more of it as people are encouraged to compounds the impression. Nearly as long as Angels in America and reminiscent of 24 hour rolling news, it isn’t just the content of what Paintin and Stenhouse say but the combination of the unhidden autocue with the livestreamed images which add up to an aggressively live experience, artificial but unflinching. Paintin notes that it really is a “forty-five thousand-word epic, and if you stay for the whole six hours it really feels like that.” It’s so large, indeed, that feedback to the two in person has often amounted to pointing out favourite parts or asking how long it took to write.

Another of Action Hero’s durational works, From Ashes had a more apparent participatory requirement, allowing people to build a city from paper; at the 21st Century Museum in Kanezawa and Forest Festival in the UK, an architect helped to design to-scale representations of over a thousand miniscule buildings local to the areas. After covering the tiny city in ash, audience members were involved in gradually removing it until the city stood again. By turns in their very diverse performances, Action Hero draw in and implicate their audience by dispensing with expected lines between process and performance, or laying bare the arenas of their pieces for inspection.

Slap Talk’s duration might scare off and puzzle, but it’s ultimately hardest on Paintin and Stenhouse themselves, “an endurance test,” as she describes it. As with all tests, the result teaches and sheds light on things in us, performers and audience alike, even if only our own discomfort or limits. It’s funny, pervasive and destabilising – whether more Abramović or van Hove, you can’t afford to pass that up.