This is a good one. I often have students that just want to learn how to go faster or they push to be a "fast rider". I've been known to say, "slow down, learn the skills and the speed will come." This is how learning occurs, if you bring the pace down a bit and focus on learning the skills properly then the speed will actually come without you even trying to go faster. Often when you try and go fast, you make more mistakes, you ride raggid and you aren't smooth and those mistakes combined, slow you down a ton.
I even just told my 11 year old son this. We were riding motocross and he saw that I had my go pro on so he whipped up the pace to try and show off for the camera. I followed him while he made about a hundred mistakes, and then he crashed. When I showed him the video I pointed out how many small mistakes he had made and how much it was slowing him down AND that his big crash could have been avoided had he not been trying to hard to go fast. Smooth is fast