Avoiding violent reaction in Flexible Objects

Lets suppose I have a flexible long cylinder linked to a cube in the stationary face of the Cylinder. Both objects are in a vertical position.
Now, suppose I want to make a quick 90 degree rotation of the cube (in one step). You will see that the flexible cylinders is violently shaked. I want th cylindre to remain in a flexible vertical position with the top curved in accordance to the cube when it is rotated. Is there a good approach to do it?
I tried to maximize the gravity and the axis forces but still have a violent reaction to the rotation.

Note: In the real case, the objects are more complex, the basic cube and cylinder are only mentioned here to make a simple example.

Sounds like a bug. Typically, increasing the drag should help, but sometimes Flexi goes out the door.
It is, after all, still relatively new.