How to build a fast quad?

I have read a news:
On July 13th, 2017: DRL joined The Guinness book of World Records to fly the custom DRL Racer X.
DRL’s RacerX succeeds in world record attempt. They got the fastest speed: 179.3mph.

That’s a amazing speed, but I don’t need so fast speed, I just want to know how to build a fast quad, what should I do, what quad parts I need?What’s the biggest factor for the quadcopter flight speed?

I don’t want to build a quad like the DRL Racer X, I want to build a fast speed drone, just flight fast, so what should i do?

Well, you should put first thing that calculating the thrust-to-weight ratio.

You need to make it very light and with loads of thrust, sounds simple but it isn’t, how fast is fast enough for you?
I have built a tarot 650 machine an this can do 40mph, small racers do 60 and more but there is also a trade off, the faster you go the less flight time you get.
Check it is only $2/month and you can do some estimates with it.
It will also help you to understand how all parts work together.