Besides the stress and drug use, something else that could factor into this is the fact that speedrunning is about memorization and familiarity with a game. Case in point, this video where somebody donated money to "casual streamers" for them to pull off speedrunning tricks. This video's noteworthy because it pretty much proves that speedrunning is about memorizing and practicing tricks to play through a game faster.I never asked this because it's pretty late to ask something like it but are there are theories on why he performed so bad in that event? He did well enough to be in the finals and stress never factored in for him when doing top-tier speedrun streams.
I mean he lost so-fucking-bad. How come? Did he have a drug habit back then and maybe a flashback kicked in right then?
Cosmo was being made to play an unfamiliar game with an unfamiliar level (one made just for the tournament). He couldn't memorize the level beforehand so he had to have some knowledge of the game mechanics. Thing is, I googled and the only time Cosmo speedran a Mario platformer I could find at least was Mario 64. If he had known some more Mario mechanics (especially with NSMB) he might have done better.