Go into your nVidia control panel and disable vsync for any applications you may have running in the background, like your browser, discord, spotify etc.
I was getting this weird issue where a lot of the time I'd be reduced to 48-49 FPS except when looking at the sky/ground/less built up areas. This seems to have solved that issue. Worth a shot!
E: Here's a wee guide on how to do this
Right click this in the bottom right of your taskbar
Select "Open nVidia Control Panel"
Go to Manage 3D Settings, select the application you want to apply this to, scroll down and set "Vertical Sync" to "Off"
Repeat for anything else you might use.