Vice is not a "slow" movie, nor is it pedantic. Vice does require intense attention to each participant and the environment, as it should, for the writer and director show common people in extraordinary circumstances.
Madsen and Hanna may not seem "common", but see them at the bottom of the ladder in their environment. The acting is exquisite, the sets sublime (in the sense that they disappear and yet contribute a force on the viewer), and all is wholly believable.
Vice is paced to the stark reality of an undercover existence, of competing loyalties, of personal trust and values, of redemption. Best of all: It takes until the very end of this film, but there is resolution.
A hard film, but well worth the effort.