Does Vsync causes system to overperform?

Vsync means it will lock to that framerate and only that FPS

The only way this would be an issue is if your hardware isn't capable of that level of performance

not the cpu but the gpu, i see your running the 1660ti, that should be good for 72fps as your screen is set to 72hz.

check that ultra low latency is not set to on or ultra as that knocks fps off. check if vsync is on global in nvidia control panel and off in game as you stated its all default, if default then global vsync will be off. in game vsync tends to be useless. are you running the game in fullscreen or borderless mode (borderless can hit the fps too)

i know this game does have performance issues sometimes, there is the glitch about where it stated 0% gpu use but is actually using it.

do you have anything new installed on the system where it could be running in the back ground, have you enabled recording in the background for gamebar or shadowplay at all.

check for an updated driver, set vsync globally in the nvidia control panel and off in games that you play. do you have game dvr running in the background as that can cause issues with a low memory GPU.

I always get a crash with the same exception code and referencing nvwgf2umx.dll whenever I try to stream if I have vsync forced to fast or adaptive vsync in nvidia control panel. If you force vsync setting, try changing to application controlled to see if
it helps with your issue.

I've discovered that with Borderless Windowed and upon a restart of system and loading of intro level room, that at 3840x2160 with RTX On. Shadows On. Reflections On and VSYNC On that I'm getting a locked 60fps in 1st level intro room.