Rails extremely slow on simple static render - ruby-on-rails

Question

I'm relatively new to Rails, but decided to develop my new project on this platform. I'm using new Rails 4 framework based on Ruby 2.0 and Unicorn as application server served through Nginx.
After some initial development I deployed my application to Amazon EC2 small server, and was literally shocked by the slow performance, testing it with simple ab utility. Giving you more details:
unicorn config file:
# config/unicorn.rb
env = ENV["RAILS_ENV"] || "development"
worker_processes 1
listen 8080, :backlog => 64
preload_app true
timeout 30
pid "/tmp/unicorn.mysite.pid"
if env == "production"
working_directory "/mypath/current"
user 'ubuntu', 'ubuntu'
shared_path = "/mypath/shared"
stderr_path "#{shared_path}/log/unicorn.stderr.log"
stdout_path "#{shared_path}/log/unicorn.stdout.log"
end
before_fork do |server, worker|
if defined?(ActiveRecord::Base)
ActiveRecord::Base.connection.disconnect!
end
old_pid = "/tmp/unicorn.mysite.pid.oldbin"
if File.exists?(old_pid) && server.pid != old_pid
begin
Process.kill("QUIT", File.read(old_pid).to_i)
rescue Errno::ENOENT, Errno::ESRCH
end
end
end
after_fork do |server, worker|
if defined?(ActiveRecord::Base)
ActiveRecord::Base.establish_connection
end
end
routes.rb:
root to: "home#index"
home_controller.rb:
def index
render "index", layout: false
end
and index.html.erb is just mostly static 3kb file
There are no DB queries, Unicorn running in production mode, partials cache enabled in Rails.
ab -n 1000 -c 100 http://myinstance.amazon.com/ returns like 30-40 requests/per second performance, and average 3-4 seconds response time with 1 unicorn's worker(remember I'm using small 1cpu instance), and even less when increased to four. Strange enough when I tried to test the application on amazon's medium instance, it didnt improve the performance, giving a hint that it's probably limited by disk io. Well, when I replicated the same simple application on PHP and node.js stacks, that I used before, significantly better performance(more requests per second served with much shorter response times) comparing to the above mentioned Rails.
Is it normal for a Rails application? Any hints how to improve performance? Maybe some configuration tweaks? I tried to search, but I see mostly general information about Rails code improvements that do not apply here due to oversimplified example.
UPDATE #1
I include pieces of production.log on request, they vary from:
I, [2013-07-20T13:21:44.830189 #1852] INFO -- : Started GET "/" for xx.xx.xx.xx at 2013-07-20 13:21:44 +0000
I, [2013-07-20T13:21:44.831420 #1852] INFO -- : Processing by HomeController#index as */*
I, [2013-07-20T13:21:44.832519 #1852] INFO -- : Rendered layouts/_head.html.erb (0.5ms)
I, [2013-07-20T13:21:44.834213 #1852] INFO -- : Rendered layouts/_header.html.erb (1.5ms)
I, [2013-07-20T13:21:44.834966 #1852] INFO -- : Rendered layouts/_footer.html.erb (0.0ms)
I, [2013-07-20T13:21:44.835143 #1852] INFO -- : Rendered home/index.html.erb (3.2ms)
I, [2013-07-20T13:21:44.835356 #1852] INFO -- : Completed 200 OK in 4ms (Views: 3.5ms | ActiveRecord: 0.0ms)
to:
I, [2013-07-20T13:21:44.689225 #1852] INFO -- : Started GET "/" for xx.xx.xx.xx at 2013-07-20 13:21:44 +0000
I, [2013-07-20T13:21:44.690629 #1852] INFO -- : Processing by HomeController#index as */*
I, [2013-07-20T13:21:44.716144 #1852] INFO -- : Rendered layouts/_head.html.erb (24.7ms)
I, [2013-07-20T13:21:44.718191 #1852] INFO -- : Rendered layouts/_header.html.erb (1.7ms)
I, [2013-07-20T13:21:44.718919 #1852] INFO -- : Rendered layouts/_footer.html.erb (0.0ms)
I, [2013-07-20T13:21:44.719042 #1852] INFO -- : Rendered home/index.html.erb (27.7ms)
I, [2013-07-20T13:21:44.719280 #1852] INFO -- : Completed 200 OK in 28ms (Views: 28.2ms | ActiveRecord: 0.0ms)
UPDATE #2
I tried to make 10000 consequent requests and server simply timed out in the middle
ab -n 10000 -c 100 http://myinstance.amazon.com/
This is ApacheBench, Version 2.3 <$Revision: 655654 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/
Benchmarking myinstance.amazon.com (be patient)
Completed 1000 requests
Completed 2000 requests
Completed 3000 requests
apr_socket_recv: Connection timed out (110)
Total of 3457 requests completed

Answer 1

It seems that it is quite expected result. You compare 3 different things: full-featured framework (Rails), platform (Node.js) and language (PHP).
Let's see how we split the response time:
[total time] = [web server processing time] + [framework infrastructure time]
+ [language interpreter time] + [your app logic time]
Of course, in case if your application will do nothing, the last component can be neglected.
When you run PHP or Node.js application there remain only 2 components in the sum: [web server processing time] + [language interpreter time], so it can handle requests very fast. Rails adds here the 3d component [framework infrastructure time].
If your application will start to do something more advanced then time spent in framework and webserver can have less impact on the total time (relatively). Though JavaScript will outperform Ruby nevertheless.
To be more objective you'd better add something on top of Node.js (like Express.js) or PHP (like Yii or Zend Framework). Or use something more lightweight instead of Rails to process small request much faster (e.g. Sinatra)