Thank you for your kind help and support.
I updated the Nvidia drivers to the latest version and restarted the PC.
The problem is still happening: GPU at 99% and CPU around 38% only by executing the game (nothing else).
Surprisingly this happens regardless of the screen resolution: 3840x2160 or 1920 x 1080 or 1366x768
I tested with a 3840x2160 @60Hz native display and also with a 1920x1080 @120Hz native display. Same results.
The only difference is noticed when changing from full screen (GPU=99%) to windowed (GPU=90%) but it is not significant.
Please find attached a screen capture.
Might it be related to the number of frames per second? hmmm I don't know
Is there somebody else having this problem?