While it does not reach the category of locution and has its literal meaning, I suppose it is used more figuratively, for the effort or work that does not yield as it should. See walking, much, advance, little.
It is to perform a task, a work or any goal that is proposed safely, advancing firmly, with certainty of doing it well. In a joking way it is the person who says that it is going in a hurry but in truth it advances very slowly, like the story of the turtle that was sent by water and it took 7 years to return.