Unity 5 stuttering

Hi guys, i have a problem. a constant stuttering of the game in play mode AND in editor mode(if i move the camera in editor mode, it will produce micro stuttering too). i dont know what to touch, what to change to eliminate this stuttering. This Stuttering appears at a fixed amount of time while in play mode, lets say ever 0.5 sec and the FPS drops from 2500 to 200 and even 40, very noticeable the micro freezes. In editor it appears when changing direction of view or pressing keys.

so far i have tried:
-Restarting the editor
-trying 64 and 32 bits
-disabling Vsync in the editor, in the Nvidia panel and both at the same time.
-Nvidia Drivers updated
- i have Windows 10 Pro 64bit, I5 4690K, GTX 970 SSC, 8Gb. i tried on my old Win 7 too with the same rig.
- I suspect, in play mode, it is something related to FixedUpdate, but it only has this line of code:

 void FixedUpdate () {
           rigidBody.MovePosition (rigidBody.position+(velocity*Time.fixedDeltaTime));
 }

In the profiler you can see spikes of 99% use of the processor by the physics engine.

- I have readed other forum posts related to this problem but i havent found a solution yet.

Here a video in play mode with the profiler
https://youtu.be/CDp62AYCnK0

HEre a little video of the stuttering inside the editor, not in play mode. https://youtu.be/cW4vAZbTmFQ