This seemed to work for me.
This is only a temporary fix, until this guys at Ritual come up with something permanent.
First Save your game.
Before you walk down the corridor, change the graphics settings from DirectX 8.1 to 9.0.
Walk towards the door. Let the next part of the level load.
Save your game again. Then switch back to 8.1.
The reason being, unless you have a super fast PC, with tip top specs, 9.0 will hog all your resources & cause the game to stutter.
Hope this helps.