As late as 2013, the record for finishing Super Mario Bros. was held by andrewg1990 at 4:58. In April of this year, it was 4:57.427, and held by Darbian. Last weekend the record was tied by Kosmic at 4:57.244. He then broke it with a new time of 4:57.194. But only a few days later, Darbian reclaimed the mantel with a new record of 4:56.878.
Source: Kotaku – New Glitch Reignites The Super Mario Bros. Speedrun Race