The issues that I'm having have brought me to the brink of insanity.

Could you elaborate on what RTSS is? I'll def try this, just curious about the settings I'm messing with lol

I don't think 30 FPS is fine lmao

this doesn't resolve the issue unfortunately, just tested. in any case, it is not a stuttery framerate issue - if you check the video provided the framerate is fine, but the gameplay itself is in slow motion

Use RTSS to manually set the FPS to what you desire, and turn vsync on in NVIDIA control panel. Never put preset graphics to low as this hard locks the game to 30 fps. The refresh rate randomly appeared in my settings after messing around with changing the graphics presets. 

The slow motion issue has been ongoing for months and unfortunately the team here on the forums have barely acknowledged it. There were many threads on the issue in the playtesting forums with many users with high spec machines reporting the issue and providing their DxDiag files, but all playtesting threads are now all closed

By the way, the issue is not my PC specs. I can run GTA V at high settings at about 70fps with another monitor having a video/Discord open.

Could it be my NVIDIA settings? My drivers are up to date.