Every time i wonder , how zomato, swiggy ,doordash get the distance and time between user and service in very less time

Question

I am, curios to know, how these(swiggy, zomato, yelp etc..) application uses user location, and list all the restaurant with the distance and time from user location in very less time, and which service they are using.

Let say if i want to make similar application like swiggy so , how do i start, how can i figure out the distance and time of between user and service, when the requests made in 1000 or more.