Gemini is sort of an outlier that doesn't really fit either category well, but the micro-frameworks have a fairly consistently higher framework optimization index than the large MVC frameworks which is as expected.
Express and Sinatra really stand out as widely-used, very high percentage of platform performance retained frameworks here. I've never used Vert.x, but I will certainly look into it after seeing this. I'm very impressed that Express is so high on this list when it is relatively young compared to some of the others and the Node platform is also relatively young.
Play seems particularly disappointing here since it seems any good performance there is almost entirely attributable to the fast JVM it's running on. Compojure is also a bit disappointing here (I use it quite a bit).