Youtube user, Transgenic86, has managed to pull of what seems almost impossible, sprinting through the full Portal game in less than 10 minutes. Yes, he does use some known and new exploits, but that takes nothing away from the insane speed run that took him 2 years to perfect.
via PCgamer
Checkout the description from the Youtube video for more details,
This is it… Portal Done Pro. I, DemonStrate, beat Portal for the PC in under 10 minutes. From when I get out of bed, to the time I drop the final personality core into the furnace, the time is 9:25.567. It is the current world record for Portal completion time.
Much of the speedrun is sitting in the elevator. I have not calculated yet how much time I waste waiting for the elevators, but I'm sure it is probably a majority of the time.
I segmented the speedrun per map. This means when the game says, "Loading…", it is loading a new map, and I save the game and load from there. The only exceptions are Chambers 02 and 13.
This speedrun uses a majority of the glitches in the game. Unfortunately, it does not use the acute angle glitch, which might be the most useful glitch in the game, if used correctly