Historian James Mahaffey has a knack for sharp insights well expressed. This is a footnote of his, talking about the time it took to run the first tiny experimental reactor, from December 2, 1942, and be certain that a big reactor could be built:
It is important to note the astonishing speed of the development of a power-producing fission process. It was only 90 days. In comparison, over 50 years have passed since the first nuclear fusion reactor was built, and as yet not a single watt of power has been produced. If solar power could have been brought from lab to industry with such speed and apparent ease, we would now be running the country on sunlight.
Mahaffey, James. 2009. Atomic Awakening: A New Look at the History and Future of Nuclear Power. Pegasus, New York, p. 147