Cinema doesn’t get much more challenging than Colossal Youth, the latest from legendary Portuguese director Pedro Costa; it’s provoked audience walkouts along the festival circuit from Toronto to Cannes. Composed of extended long takes and static digital video shots, with characters talking slowly at each other in darkly-lit, disconnected vignettes threaded together by a single, wandering protagonist, Colossal Youth suggests Beckett and Chantal Akerman but goes even further by draining any residual “fun” from what might be best deemed the cinema of entropy. As if fun were the point. In his third collaboration with Cape Verdean immigrants living in the Lisbon slums, Costa reports on the despair of poverty and the forced relocation of a marginalized community. After being deserted by his wife, retired laborer Ventura spends the course of the film visiting his “children,” younger denizens of the projects to whom he’s become a spiritual father. The monotonous monologues — including a continually recited missive that serves as the film’s harrowing refrain — waver between tedious and mesmerizing, while the chiaroscuro tableaux, mostly contained within choked interiors, simultaneously transfix and tend toward over-stylization. As always, Costa delivers undeniable material culled from the depths of hell, but appreciating it while fighting Colossal Youth’s substantial dead time proves an arduous, if ultimately rewarding, task.