What I've said Umberto, is the fact that when I uninstall GSX then P3D shuts down completely and no other app complains that it still runs in the background.
That doesn't mean GSX is the cause. Only that no other addon you have installed is using the new and highly efficent PDK method for some function which, being more low-level of Simconnect (that's why it's faster), might be AFFECTED by a problem with video drivers or video drivers settings.
I hear what you've said, it doesn't make sense that video drivers will be the cause of this, but I hear you.
I said they might, instead. And it seems they did...
Still doesn't explain why it will only be on my rig and no one else's but let that mystery die one day when I go through another cycle of upgrading my PC.
Maybe it wasn't just an issue of "faulty" video drivers (even if nVidia HAS released a faulty driver recently, up to the point that it caused blue screens with the latest Windows 10 update), but also a combination of a particular video driver release and some tweak or setting in them that might have been removed when installing the new version.