Subways will always tend to be faster, just because they don't have cross traffic enforced by cycling traffic lights. Traffic lights are just a reality of street-based transportation, because the light length needs to be long enough that someone like a grandma with mobility issues needs enough time to cross the street.
Traffic lights can be tied to bus traffic - if a bus approaches give it way (both by letting other traffic flow away as well as keeping green till the bus crossed) Doesn't work for all situations but can give 80% green wave, even where bus lines cross.
However then bus is still slower than a subway on long distance. A subway can take a more or less straight line, while busses have to follow roads. Also passengers typically expect denser stops with busses. Also by being alone on the track a subway can go faster as max speed.
But even with subway on long distance, bus can connect with high density to subway, so that more people can reach the station.
