Slippery Physics

Slippery physics is an irregular state of the game's physics engine. On most platforms and versions of the game, it will be activated at random upon map load. On the Linux version, this state is always active. For the Windows releases it's possible to ensure that slippery physics are always enabled by activating compatibility mode in the game's launch settings. Selecting any of the operative systems seems to do the trick, though runners most commonly select Windows 7.

It seems that AMD Radeon graphics cards run into a stutter issue with slippery physics.

There is a video tutorial on slippery physics, among other important settings, in this video.