gistfile1.txt

require 'benchmark/ips'

env = {"foo" => "bar", "bar" => "baz", "baz" => "boo", "PATH_INFO" => "foo"}

Benchmark.ips do |x|
  x.report("set and reset") do
    env["PATH_INFO"] = "zoo"
    env
    env["PATH_INFO"] = "foo"
  end
  x.report("merge") { env.merge("PATH_INFO" => "zoo") }
  x.report("dup") { env.dup["PATH_INFO"] = "zoo"}
end


Calculating -------------------------------------
       set and reset     72210 i/100ms
               merge     32360 i/100ms
                 dup     40064 i/100ms
-------------------------------------------------
       set and reset  1505441.3 (±10.3%) i/s -    7437630 in   5.001122s
               merge   440993.4 (±13.2%) i/s -    2168120 in   5.020391s
                 dup   603567.4 (±7.9%) i/s -    3004800 in   5.011971s