Speedrunner 097AceOfSpades beat Portal in 52 minutes using no portals and a lot of airboat cheats.
Usually, Portal takes about three hours to complete. And, as the title implies, you complete it by using portals to solve the game's tricky puzzle-based campaign mode.
097AceOfSpades relies on one main hack to get through the game sans portals: Spawning airboats. They're assets from Valve's Half Life 2. Because Portal was made with the same engine, 097AceOfSpades says, he's able to spawn them in Portal to help get around puzzles. That way, he can climb on top of the structures to reach platforms or, by spawning airboats midway through walls, he can use them to clip through locked rooms:
Sometimes he'll spawn a few dozen airboats that launch him onto higher platforms like so:
The fastest Portal speedrun with portals is about eight minutes.