small cms. read posts from file or mongodb

Consider I have a web site written in nodejs, and now I want to write a small CMS for it. for managing posts, articles and ...

my question is, when user request a page that contain some article (raw text), i must fetch article's data from somewhere (database/file/...) and put in html file, and then send back to user.
which is better and faster? save raw text(articles and ...) in files or in mongodb?
Or anyone know better way to create this simple CMS.