Resolved Low FPS

What's the technical reason behind that and how do you measure the input lag difference?

 

Is there a simple tutorial on how to do this? I always use vsync too but I'm always open to new ideas.

 

I know this is an old post but I fixed my constant 30FPS on R3E by disabling vsync. It now runs 70-100 FPS with everything turned to max.

My Radeon RX 5700XT is now running at 90-95% GPU vs. 30-50% prior to turning off vsync.