We try to slow things called fast neutrons down so that we can initiate a nuclear fission reaction. Doing this produces loads of heat that we use to boil water into steam and turn a turbine-generator. Efficiency is key to our process and we always try to improve on this.
I don’t make things go fast, but I am trying to make solar refrigeration more efficient. If we can make it more efficient then we can make the machines smaller and they will be easier to move around (so doctors could carry around important medicines to ill people in places that are difficult to get to). Also making the machines smaller means they will cost less to build, so more people will want to use them instead of the normal electric powered refrigeration.
Wow. What a question. Particles in Fusion do go very fast – fast enough to go around the world in one second, except that they only travel in straight lines!. We are trying to make the conditions in the sun and other stars on earth. That would be efficient, we hope. Regards Robin