How much does your web framework choice affect performance? The answer at Framework Benchmarks page may surprise you. Netty, Vert.x, and Java servlets are fast, but the researchers were surprised how much faster they are than Ruby, Django, and friends. Here is one graph from Framework Benchmarks page that shows you the results.
If you want to repeat the test yourself, Framework Benchmarks page has the source code for the tests. Those source codes give you also idea how the code looks on the platforms you don’t already know.