I've been playing the new 1.9.0 version for a while... and I couldn't help but notice how moving the camera around / moving your head (using the R stick to look around) causes an immense drop in framerate. The framerate is usually consistent when moving with the L stick, simply walking, but at the slightest camera input with the R stick the game starts stuttering and lagging and goes back to normal as soon as the stick goes back to neutral position.