slice.rb

require "benchmark"

def f(i); i; end

array = Array.new(1_000_000) { rand.to_s }

TESTS = 5
Benchmark.bmbm do |results|
  results.report("null:") { TESTS.times { array.each { |i| f(i) } } }
  results.report("sliced each:") { TESTS.times { array[1,array.size-2].each { |i| f(i) } } }
  results.report("ranged each:") { TESTS.times { array[1...-1].each { |i| f(i) } } }
  results.report("each on range:") { TESTS.times { (1...array.size).each { |i| f(array[i]) } } }
end

# Rehearsal --------------------------------------------------
# null:            1.790000   0.000000   1.790000 (  1.827684)
# sliced each:     1.780000   0.000000   1.780000 (  1.791690)
# ranged each:     1.780000   0.010000   1.790000 (  1.796526)
# each on range:   2.360000   0.010000   2.370000 (  2.369797)
# ----------------------------------------- total: 7.730000sec
#
#                      user     system      total        real
# null:            1.810000   0.000000   1.810000 (  1.817914)
# sliced each:     1.800000   0.010000   1.810000 (  1.813449)
# ranged each:     1.800000   0.000000   1.800000 (  1.798177)
# each on range:   2.340000   0.000000   2.340000 (  2.363105)