The cameras take 90 images in a second. It does not just end here. Furthermore, the cameras also click 20 LIDAR images within a second. This gives a precise and accurate account of the nearby surroundings.
These images are used to access data points to determine the location relative to the camera and then plot the map accordingly. Furthermore, these calculations require fast processing that is available only in GPUs. Near about 20-100 calculations take place within the time frame of a second.