I went to Fabian's tutorial for it at TABConf back when it was first merged. I remember the database being pretty large and slow to download. Also, it updates every few seconds. It is another thing that eats band and you have to run it all the time. Not saying that's a bad thing, but it has a cost.
Discussion
way faster now! try it https://github.com/asmap/kartograf
And no you run it once and it produces a file. Run it again when you want to update. No bandwidth cost, little compute cost.