tornado sport is only rated marginally faster than the N20(and that is with the best sailors in the world setting the rating) making them pretty equal boats. It's not the beam it's the entire package.
The N20 rating was set when Smyth was racing it. And yes, the beam has a huge part in it. In light air, the boats are pretty close but when it picks up past 8knots, the T is much faster.
