I plan on benchmarking on thin, unicorn, puma, WEBrick, torquebox 3, torqbox (torquebox 4), trinidad, passenger, and I guess now Jubilee.

I was also thinking of doing some EventMachine based stuff like goliath and whatever else I can find in that space.

From my early benchmarks last weekend torqbox is the fastest and pure rack is a lot faster than sinatra or rails. Sinatra is not nearly as fast as I thought it was compared to pure rack. A simple thin server running ruby 1.9 got about 1500 req/sec for hello world using Sinatra. Torqbox and jruby brought that to about 5000 req/sec. Plain rack was about 6500 req/sec on ruby 1.9 and thin and on torqbox it was 10,250 req/sec. For reference, my golang hello world was getting 10,500 req/sec.

I'm very curious where Jubilee will land in that mix.

My laptop gets 19k req/s with Jubilee and 118k req/s with TorqBox on the same Rack app. While Java on Vertx does fare very well in benchmarks, it's incorrect to assume this directly translates to other languages and frameworks written on top of Vertx also having the same high performance.