There’s different varieties of speed running. Some people do it entirely manually, others do Tool Assisted Speedruns (often abbreviated to TAS) where a program

There’s different varieties of speed running. Some people do it entirely manually, others do Tool Assisted Speedruns (often abbreviated to TAS) where a program provides all the input, allowing frame perfect moves which humans are incapable of. There’s also a slowly growing trend of letting machine learning algorithms loose on games like Mario - that stuff to my knowledge is still at the stage of trying to get an AI to even be able to finish the game at all, but I’m sure with some time and effort we’ll start seeing techniques no one has even thought to try.