inject_test.rb

require 'benchmark'

def each_acc list
  foos = []
  list.each do |letter|
    foos << letter.to_i
  end
  foos
end

def inject_acc list
  list.inject([]) do |memo, item|
    memo << item.to_i
  end
end

n = 50000
LIST = ('a'..'z').to_a

Benchmark.bm(7) do |x|
  x.report('each') do
    n.times { each_acc(LIST) }
  end
  x.report('inject') do
    n.times { inject_acc(LIST) }
  end
end

results.txt

             user     system      total        real
each     0.810000   0.000000   0.810000 (  0.823612)
inject   1.600000   0.010000   1.610000 (  1.608838)