If you follow the retro gaming scene on Twitch, it's likely you spend a decent amount of time watching speedrunners. It can be fascinating to see how older titles are manipulated, streamlined and mastered over hundreds of hours, and if you happen to catch a world record live it can be an exciting community moment.
One of the true golden standards in speedrunning, Super Mario Bros., has been a focus of attention as players looks to shave individual frames off the record. Recently a major landmark was hit, and so strong is the optimisation of the speedrun for the game, it may never be broken again.
Niftski set a time of 4:54.948 for Any%; that's the first sub 4:55 time ever, and at this point it looks extremely difficult (perhaps impossible, but the community may keep trying) to ever record a 4:53 time. You can see the run below, just be aware that there's a lot of excitement so the video gets loud when the run ends.
Some of you may be wondering about the fact this is being played through an emulator with a keyboard. It's worth noting that this run has been verified by speedrun.com in the main category, though as you can see those that don't use original hardware have an 'EMU' under platform. When it's a hardware-accurate emulation the records do stand, so it's all above board.
Of course, others can chase to improve the record by a matter of frames, but we may never see it go as low as 4:43.