Benchmark

Returning an array as a response:
[200, {'Content-Type' => 'text/html'}, ["<h1>Hello!</h1>"]]

Benchmark:
  10000 runs
  0.037738 seconds total
  0.0037738 millisec/run
  
With a controller rendering a template with erb:

Benchmark:
  10000 runs
  2.366915 seconds total
  0.2366915 millisec/run

With a controller rendering a plain html file:

Benchmark:
  10000 runs
  0.606326 seconds total
  0.0606326 millisec/run  

With a controller return a simple text:
'<h1>Simple Text</h1>'

Benchmark:
  10000 runs
  0.094172 seconds total
  0.0094172 millisec/run