DC Metro is slow and unreliable? Are you talking about the correct thing? The DC Metro is excellent and usually features 2 tracks.
If you are talking about MARC real trains, somewhat correct. Camden line is a freight line, part of the oldest line in the country, and can be a bit slow. Penn line is passenger, though, and is plenty speedy.
Neither of which matters when at least you can rest, work or goof off while waiting for that commute rather than having to stay alert and not make any mistakes during it.
I was talking about the DC metro. I lived in Japan and saw how trains can work. In Japan you could cover twice the distance in half the time of the DC metro. They also have express trains which skip the minor stops. If you live at a minor stop it is faster to catch the express to the closest stop and then wait a couple minutes for the local to your stop.