Just having experienced this problem myself, I asked google and found this thread. When moving around the map (Im not using tiled), the screen seems to get a small shunt or lag at a regular interval of about 1 second, even when I am multiplying my movement values by the delta.
I added in a for-loop to render all of my graphics 100x per frame, and the stuttering disappears completely. Very strange!
Does anyone know what is actually causing this? Something to do with the frame rate timer libgdx uses perhaps? It seems to me to be something that shouldnt really happen.