What is the reaction time of the Arduino interrupt?

Using Arduino General Electronics
25

I cannot imagine you wrote your answer on a PC/notebook that runs with less than 1 GHz. When it comes to speed, the MHz and GHz do count.

Your example (traffic light) is only valid when booting a system. A Ferrary can reach 100 km/h in less than 4 seconds. How many meters will you be able to cover in 4 seconds?

I do love my two Arduinos.

However, when it comes to real speed, the Arduino might not be the proper solution.