They only improve speed from an initial "get it working" point of view. That's part of the reason flask is rarely taken seriously as a production solution. Not having natural separation between views and urls is a real PITA for anyone trying to create a long term solution or larger project. For what it's worth, I also hate the argument that bad design increases Dev speed. That's only true until you need find something later, then you have to hunt around instead of having one place to look, wiping out any initial gains. It's false economy.