Here's a great piece of footage from the 2011 F1 qualifying at Suzuka, and it demonstrates just how precise you need to be to defeat your rivals. Show 99% of people this footage with no commentary and they wouldn't even notice the differences. The exact line taken through each corner, and track position and attitude of the car, all of this adds up to dictate your final laptime. The tiniest of changes can mean the difference between victory and defeat, as we see here.
If you've got a decent amount of GoPro footage of your kart, it's time to start analysing it in much greater detail.