Drums would be WAY more efficient than discs were it not for one thing. They cannot dissipate heat like discs. If they could and not fade, drums would be on everything made still today. Unfortunately, that's not the case. After three or four hard stops, drums heat up and fade.
All that said, I am a BIG proponent of drum brakes on a street car. Even a race car down as fast as high 10s. Drums are better than discs.....until they begin to fade. Look at the difference in the surface area of a drum brake shoe VS a disc brake pad.
Drums are also much lighter than their disc counterpart. Drum brakes can stop unbelievably quick as long as they are in good working order and have not been neglected. I plan on keeping the drum brakes on my 65 Coronet and it's not gonna be slow with a big block and 4.56 gears.
Road racing? Drums probably not a good idea. I would run them on a drag car real fast. Since they don't have to repeatedly stop and they are light, they are an excellent choice down to a certain ET. JMO.