Hi Goran,
First of all, the TBM is an awesome airplane and I can't thank enough for it.
Those pictures come from X-Plane's own data graph, so no plugin is used here (to rule out any suspicion of conflicting plugins).
The problem is, that the stuttering is really evident, and it's like flying in "small increments", smooth for a bit and then a stutter. If you want I can send you a video of this.
Thanks again,
Gabriel