This then provoked me to do some basic math. Imagine a real world startup scenario wherein you need to your application to deliver API responses (JSON) or even ordinary HTTP responses. If you use a framework from the bottom of the list (like Rails), then you may be able to serve, say, 'X' customers on your site using your application at a time. Now, if you use something from the top of the list, you may be able to serve roughly about 20 times (20X) more number of customers on a single server. This not only means less cost, it also means you can worry about scaling and stuff much much later than you would have to, unlike on a low performant framework.
For this reason, I decided to conduct an experiment for myself. Pick up a framework from the top of the benchmarks and experiment with the learning curve and the language. Well, after carefully evaluating, I decided JAVA wasn't for me (too much of a beast). But Scala seemed to hit the sweet spot with excellent language (1 line of Scala = 10 lines of Java on an average) features along with the trust of the JVM.[1]
So, I chose Scala and started experimenting with it. I started with the play framework and was not fond of certain decisions that were made within the framework. Also, the play framework is nothing like Ruby on Rails (but it claims to be so) and was more of self-serve and also quite heavy for my taste. Hence, I went even farther up the list and chose Scalatra. Generally, framework selection is a matter of personal preference and each one should choose whatever aligns with their philosophy. For me, it was scalatra.
Frankly, I haven't been able to ship out features at the speed at which I used to, with Rails, but there was something very important that I learnt too - Don't get comfortable with full stack frameworks without understanding what goes underneath. Rails suddenly seemed like an enemy to me because it was doing everything so magically that I literally had NO IDEA until I had to implement them myself with Scalatra. For example, do you know what AES-GCM is? Do you know HOW the secure cookie store in Rails works? What algorithm it uses?? Do you know you have to change the secret pretty often??? Do you know how authentication in Rails (Devise) works??? Can you build it from scratch???? I knew none of these, until I had to implement them myself for my application on top of Scalatra. It was seriously a pain because for the first one week, I did absolutely nothing, in terms of progress with features. But later, I started loving this way of development rather than relying on 'magic' frameworks. Now 'magic' seems scary for me because I cannot actually see what's happening underneath.
So, to cut a long story short, Should you choose the fastest framework? Or should you follow the 'ship it first' policy with an average framework??
My advice - Start with a full stack framework, something like Rails or Django, but also in parallel, try to understand how every bit of your framework works and try to implement it into a micro framework based on something from the top of the benchmarks (like Go, Scala, etc.). Most importantly LEARN. Something new everyday! And slowly shift your development towards these high performant frameworks as and when you see fit.
This is just based on my experience :)
[1] 1 JVM = 10 Thins, Source: http://www.slideshare.net/pcalcado/from-a-monolithic-ruby-on...