Material nodes bug.

Before I post a bug report, has anyone else had a similar experience?

I’m using blender material nodes quite a lot in this project and getting data from global co-ordinates rather than UVs to control such things as height based mist or UV scrolling.

You can see my problem here.
There’s no error in the console, no reduction or increase or any kind of change to the profiler…
It only affects objects with material nodes and only those getting info from global mapping co-ordinates.

It affects every visible object in the scene. It only happens from very specific angles and positions of the camera.

The freezing isn’t the bug, that’s just me pausing the game to show that the flickering is caused by camera angle, not by timing.