The quest to complete games have existed since around the 1980s time period but only picked up popularity in the world around the 1990s when the internet become more popular for regular people overall.
What is the basic point of speedrunning?
To try and complete a videogame as quick as possible this can be done many ways such as simple studying yourself or watching other people complete games then finding ways to copy what they do this can include learning how they jump by say completing the jump quicker by completing jumping you do it faster by say jumping to the left hand side which could maybe increase speed of jump if the system goes from left to right some of the time.
Older consoles often can only go at certain speed rates over limited of the past in regards to software or game fame rates which were used before.
A very smart man who works out this Youtube known as Karl jobst you can learn more about this on his Youtube channel as shown here.