Besides, it only optimizes the non recurring user case - 10x improvement is only for the first time visitor, which may or may not be a minority or even then may

Besides, it only optimizes the non recurring user case - 10x improvement is only for the first time visitor, which may or may not be a minority or even then may or may not have the font in cache from other places, which is not unlikely especially if he used a font from the most common cdns.