Nvidia preferences vs Unity application preferences (performance question)

Hi!

This is quite well known that Unity games are being launched on most of notebooks with integrated graphics by default which sucks and leads to poor performance for some users.

Same time, we have just got a case of someone who had really bad FPS while we were expecting our game to run smoothly at this notebook. After looking closer to his system settings he had a Nvidia settings set into "Use 3D application settings" - nevertheless even with using lowest settings of our application his fps were about 10-15.

When we changed his Nvidia settings from "Use 3D application settings" into "User preferred" and set it into "Optimization" he got 60 fps constantly.

I would like to ask, how is that even possible? Anyone have idea which Unity based application settings are being checked while using Nvidia settings from "use 3D application" settings?