Some great advice on here.
My rule is that you will go faster if you slow down less (stay with me…!). That equates to smoothness. And smoothness comes from the following (as examples):
Looking ahead changes your perception of speed. If you look down things will appear fast so your mind will react to that perceived speed e.g. you will touch the brakes. If you look up things will appear slower so you will brake less. This is on top of the benefits of reading the trail and setting the bike up for what’s next.
Everyone can just muller it flat out but its the corners and choice of lines when things aren’t just a smooth straight path that will give you speed overall. In addition position on the bike (e.g. pedal position and weight distribution) and inputs (e.g. leaning the bike, pumping, bunnyhopping, manualling) all help keep the bike at speed.
There is a certain amount of sense in the death grip mentality too. There’s a great vid on youtube about how to get faster. The guy very convincingly just tells you to resist the temptation to brake and see what happens. It really works.