"Narrative momentum" refers to the driving force or energy that keeps a story moving forward. It is the sense of progress or development in a story that keeps readers or viewers engaged and interested in what happens next. Full definition
A deliberately paced literary film that takes too long to build narrative momentum and explore its central dramatic conflicts. (metacritic.com)
But there's also no attempt at narrative momentum from movie to movie anymore. (chron.com)
The director's objective is to emphasize drama over suspense and, as a result, the kind of fast pace and narrative momentum often associated with a thriller is absent here. (reelviews.net)