So you're at speed. And in the distance you see a red light. At this point you don't know how long the light has been red. It could have just changed or it could be changing to green any moment. What do you do?

Do you continue to pedal at speed on to (maybe?) have to mash the brakes to stop at the light. Or do you slow your peddling down - coasting even - so that if you do stop it's you're not burning off wasted effort.

Just curious. This of course assumes you're riding solo.