Superfast Mario Bros. 3 is a ROM hack of Super Mario Bros. 3 that modifies Mario to be really fast. So fast that it's very hard to control Mario due to how fast he can go. He's faster than P-speed when running, and yet the P-meter isn't filled up instantly as the mechanics for that haven't been modified, only that he can go fast instantly and stop at a dime.
In this run, Asumeh takes advantage of Mario's newfound insane speed to easily clip through walls and stomp Boom-Boom into flashing explosions along the usage of warp whistles in order to complete the game as fast as possible.
Watch this run being played back on a real console.