Japan hopes to build world's fastest computer Japan had the world's fastest computer, with a speed of 35.9 teraflops, with their earth simulator but they lost the title to IBMs 136.8 teraflops cappable Blue Gene in 2002. Now Japan is hoping to build a supercomputer that can run at 10 petaflops per second. If they get the approval from the ministry, the project could cost Japan around $714 to $893 million.  ¶ 8:40 AM