The hymn sung immediately before the reading of the Gospel is called a Gradual. This does not mean that it has to be sung very slowly. The name gradual is derived from the Latin word gradus, meaning a step. So “gradually” originally meant “step by step”.
To read more about this, and to see how steps and the architecture of church buildings are related to early understandings of theology, have a look at What makes a gradual hymn gradual.