Kirua recently broke the world record for glitching through to the end of the game and now believes the best possible time is only a few seconds away.
Two years ago, the speedrunner set a personal best time for completing the game at just under four minutes. Earlier this week, he came in at 3:05.633. That was thanks to an expertly executed glitch in the final seconds that Kirua said he'd never even been able to successfully pull off in practice before, despite holding every first-place record in the game.
More recently, the French speedrunner was able to scrape another second and a half off his record in a subsequent 3:04.05 run a couple days ago by getting a nearly perfect roll on the hammer bros. RNG in the first World. You might remember that anytime there are hammer bros. on the map, they randomly relocate after every level you complete.
Kirua notes that depending on how many movements they do each time, you can lose up to an additional 2.13 seconds. On his world record breaking run last week, he got one of the less optimal rolls on this part, but made up for it with his skill in 7-1. Late this week, he got the second most optimal set of hammer bros. movements. This allowed him to take a slightly more conservative approach on the second leg of the run.
Basically, it revolves around pushing the boundaries of the game such that it starts operating outside of normal parameters. But filling the game up with specific values by killing certain enemies in certain locations, you're able to get it to load up the very end of the game where Mario walks into where Princess Peach was being held prisoner by Bowser.
Kirua put together his own tutorial for how to actually pull off the trick with just a few hours of practice, and as commenters have pointed out, it works. While it's difficult to pull of the trick as quickly as humanly possible, it's very possible to trigger the glitch if you play around with the level enough times.
"For runs like that (either best or second best RNG), I use a small variation of the setup in 7-1 that wastes approx one third of a second, but massively increases your chances to finish a run (although the probability of success remains very very low still, to be clear)," he wrote in a thread on the subject.
That means that in theory, Kirua is already in a position to set another world record if he's able to optimise both the hammer bros. RNG and his execution of the 7-1 glitch. In addition, there are extremely difficult maneuvers in World 1 that he could also try using in order to save a small amount of time. This led him to conclude that "All in all I estimate that if I were to do a theory TAS with absolutely everything we know humans can pull off, it would probably be a very high 3:01, barely."
He added, however, that while times like 3:03 and 3:02 are in sight for speedrunners willing to grind these final parts of the any% glitch attempt, he doesn't plan on being the one to do it.