The person who calls Tarkovsky slow is not wrong about the pace. They are wrong about what the pace is for.
Slow cinema is a formal tradition built on the premise that mainstream cinema's editing pace - designed for maximum information delivery and minimum discomfort in the viewer's attention - is also a mechanism for producing passive consumption rather than active engagement. The slow film forces the viewer to be present. The fast film can be half-watched; the slow film cannot.
THE FORMAL ARGUMENT
The slow cinema argument is essentially this: the cut that comes before you've fully processed the image is an editorial decision that manages your experience rather than inviting you to have your own. The long take that holds past the point of comfort is making you present in a way that the managed cut prevents. The formal discomfort is the point - it is the mechanism by which the slow film produces genuine engagement rather than managed spectatorship.
André Bazin, the French film theorist who wrote the theoretical foundation for the argument, called this 'the ambiguity of reality' - the way long takes preserve the viewer's ability to direct their own attention within the frame, as opposed to the cut that directs that attention for them. The slow film is a film that trusts the viewer. The fast film manages the viewer.
THE MAJOR PRACTITIONERS
Andrei Tarkovsky is the foundational figure of slow cinema as a conscious formal practice. His films - from Ivan's Childhood (1962) through The Sacrifice (1986) - use the long take and the tracking shot to create an experience of cinematic time as a felt material. For Tarkovsky, time was the primary material of cinema - not space, not narrative, but duration as a thing you can feel. The eight-minute shot of rainwater running over objects in The Mirror (1975) is the paradigm case: the shot continues until the duration has produced something that the summary of what happens in the shot cannot produce.
Béla Tarr is the extreme case: Sátántangó (1994) runs seven hours and twenty-two minutes. The takes in Sátántangó are minutes-long; some are approaching ten minutes. The film is about entropy - the slow collapse of a collective farm community in post-communist Hungary - and the form enacts the content: the film drains away, slowly, in real time, over seven hours, until there is nothing left. Werckmeister Harmonies (2000, 145 minutes) is the accessible entry point to Tarr.
Chantal Akerman's Jeanne Dielman, 23, quai du Commerce, 1080 Bruxelles (1975) is the landmark of feminist slow cinema: three hours of a housewife's daily routine, observed in real time, in fixed shots that refuse to editorialize about what they're showing. The formal argument is about the labour that has been made invisible by its domesticity - and the refusal of the editorial gesture (the cut that summarises, the close-up that guides attention) is the argument made formal.
Apichatpong Weerasethakul (Thailand) is the contemporary master: Tropical Malady (2004), Uncle Boonmee Who Can Recall His Past Lives (2010, Palme d'Or), Memoria (2021). A formal vocabulary built around Buddhist temporality, the Thai landscape, and a relationship to the dead and the past that Western cinema has no equivalent vocabulary for. The slowness is the grammar of a different relationship to time.
HOW TO BUILD THE WATCHING PRACTICE
The practical instruction: do not watch slow cinema on a laptop with other tabs open. The slow film will not survive divided attention. It requires the specific commitment of the cinema or the equivalent - a large screen, darkness, no phone. The film repays the commitment with an experience that no other mode of cinema produces. It does not survive the half-attention it receives from a viewer managing other things simultaneously.
Start with Werckmeister Harmonies rather than Sátántangó. Start with Jeanne Dielman only after you've seen at least one other Akerman film. Start with Uncle Boonmee before Memoria. The tradition rewards being entered through its most accessible works; the most extreme expressions are only fully legible once you've built the formal vocabulary the tradition requires.
The fast film can be half-watched; the slow film cannot.