There seems to be a bug in the built in physics in cocos2d-x 3.x. Or if not a bug, there is a performance issue that exists when using the built in physics engine which does not exist when using Chipmunk physics directly.
The position of the physics bodies and their sprites seem to have a jitter / instability to them.
Here is a video of the jitter: https://youtu.be/MkgolnJDjlo
My guess is that it has something to do with how the Chipmunk update is executed but I have not been able to isolate the issue yet.
I just ported this code from cocos2d 2.x where the physics was very smooth when using Chipmunk physics directly.
I also have numerous other similar games in cocos2d 2.x and cocos2d-x 3.x that use Chipmunk directly, and there is no jitter issue.
The first 18 seconds of this video show the physics jitter when the world camera setPosition and lookAt are updated each update cycle to center on the vehicle.
The last 10 seconds show the word camera setPosition and lookAt being set by following the race track ground and moving forward 120 points in each update cycle.
Note that the camera is smooth moving and there is no jitter on the centered motorbike racer. The rider that passes is the physics rider, and it has jitter at 22 seconds and 27 seconds into the video, indicating that the jitter can likely be isolated to the physics body position updating.
I have also tried moving the layer instead of the camera. This is often recommended in 2d games so that the world model is updated each update rather than the camera lookAt and position. But since the jitter seems to be coming from the physics engine, the effect is the same.
On the device the frames run at a consistent 60 fps and there does not seem to be a correlation between the jitter and a drop in frame rate. There is no significant drop in frame rate.
EDIT: Even a very minor drop in frame rate, e.g. from 60 to 59, can cause a jitter in a physics simulation.