I happen to have been playing version 1.3.9 of SCPCB, and before I got to the security room in the light containment zone, the game started acting up. The framerate would drop every time I entered a room and take at least five seconds to recover. Let's say it was running at 25 FPS. The game would drop to maybe 3 or 4. It got worse from there. Eventually, the game no longer generated doors, items, or floors or ceilings. This is the reason I stopped playing this game a long time ago.

Eh lets just say that its because of cameras. Because the camera is showing that room and more polygons is used and framerate will drop.

Less rooms on camera = Higher framerate.

DropTherapy wrote:I happen to have been playing version 1.3.9 of SCPCB, and before I got to the security room in the light containment zone, the game started acting up. The framerate would drop every time I entered a room and take at least five seconds to recover. Let's say it was running at 25 FPS. The game would drop to maybe 3 or 4. It got worse from there. Eventually, the game no longer generated doors, items, or floors or ceilings. This is the reason I stopped playing this game a long time ago.

This should help you with that, it seems to help me on some occasions: https://undertowgames.com/forum/viewtopic.php?t=6498