What's the fastest speed I can move until Pokemon Go no longer considers me to be walking?
According to reddit,
the game draws a straight line between two points and compares it to a max of 175 metres.
Although the total distance is same, the game draws an imaginary line between the two points and logs that distance. Pythagoras theorem states that c2 = a2 + b2. Therefore, 123.743 = (87.5 X 87.5) + (87.5 X 87.5). Which would be known as .12 km in your egg log, which means you can travel with 10.5 km/h per hour.