98% of the websites out there could run on python and I doubt we'd see a big performance difference.
However, I really don't think there exists a 10x difference developing in Spring. Hell, I don't think there is a 10x difference in using Struts vs Rails.
Spring development is considered slow as it brings images of enterprise shops taking several years to go through the bureaucratic red tape necessary to incorporate a new feature.
I've worked with plenty of small companies using Spring and their development/release cycle is maybe 1/2 or 1/4 the speed of comparable 'easier-to-build' technologies, but it definitely isn't 1/10th the speed to develop.