The rate of technological growth has slowed down by any measure that historians and economists know how to use. The book does a much better job making this argument than I can in this short Hacker News comment, but here is a summary of the argument that I recently wrote:
Peter Drucker has argued that the 60 years leading up to 1914 were the most innovative years in human history. A person born in 1860 and dying in 1940 would live through the first lightbulb, the first power plant, the first power grid, the first electrified city, the first electric street cars, the first combustion engine, the first cars and trucks, the first telephones and then the growth of the telephone networks to include every household, the first great oil boom, the first submarines and the exploration of the underwater seas, the development of germ theory, the sterilization of the hospitals and so the first safe surgeries, combined with the first true anesthesias, the first airplanes, the first radio as telegram and then in 1920 the ability of radio to carry the human voice, the invention of the television, the first sulfa drugs followed by the invention of the first true antibiotics, the first plastics, the invention of textiles made of plastics (nylon), and so much more than I can list. A person born in 1860 and dying in 1940 was born during one epoch of the human race and died in a completely different one, much more so than any person born in any other year. The best and most recent book on this subject is "The Rise and Fall of American Growth: The U.S. Standard of Living since the Civil War” by Robert J. Gordon.
[ Also, you write about "personal computer, the internet, and the mobile phone" as three separate inventions, but it's really just 2: computers and better multi-plexing, and even the multi-plexing is because computers got better. ]