Ruby 2.0 lazy enumerators small collection performance

enum_perf_small.rb

require "benchmark"
include Benchmark

values = (0..100).to_a

bm(10) do |bench|
   bench.report("regular") do
      values.map { |x| x * 10 }.select { |x| x > 30 } 
   end
   bench.report("lazy") do
      values.lazy.map { |x| x * 10 }.select { |x| x > 30 } 
   end
end

#                  user     system      total        real
# regular      0.000000   0.000000   0.000000 (  0.000032)
# lazy         0.000000   0.000000   0.000000 (  0.000018)

Forgive me for criticizing your gist uninvited, but your benchmark methodology is flawed in the lazy version—since you're never actually forcing evaluation of the enumerator it'll always just return an Enumerator::Lazy in constant time, virtually instantly. You need to do something like this to get a more accurate comparison of the two versions:

bm(10) do |bench|
   bench.report('regular') do
      values.map { |x| x * 10 }.select { |x| x > 30 }
   end

   bench.report('lazy') do
      values.lazy.map { |x| x * 10 }.select { |x| x > 30 }.force
   end
end