Everything about this film is slow. From the way the characters talk, the speed at which the plot develops, right down to the slow fade-to-black cuts at the end of each scene. Even the climactic gunfight plays out over the course of twenty minutes or so. This isn't a bad thing, though: it echoes the pace of the period it is portraying, and with it provides a very immersive experience.
(This quick review is part of my September 2005 "clearing the decks" exercise.)