"[A]pplying downcase once is better than calling it (possibly) multiple times?"—sawa via http://stackoverflow.com/questions/38162768/how-to-make-a-string-1st-letter-caps-2nd-letter-noncaps-3rd-letter-caps-4th-l/38163148#comment63754959_38163167

benchmark_downcase_vs_enum_downcase.rb

# "[A]pplying downcase once is better than calling it (possibly) multiple times?"--sawa
#   via http://stackoverflow.com/questions/38162768/38163148#comment63754959_38163167
#   "How to make a string 1st letter caps, 2nd letter noncaps, 3rd letter caps, 4th letter noncaps…?"
require "benchmark"

n = 1_000_000
Benchmark.bmbm do |x|
  x.report("String#downcase.chars.map.with_index {|c,i| i%2==0 ? c.upcase : c}.join") do
    n.times {
      "Stackoverflow is awesome!".downcase.chars.map.with_index {|c,i| i%2==0 ? c.upcase : c}.join
    }
  end
  
  x.report("String#chars.map.with_index {|c,i| i%2==0 ? c.upcase : c.downcase}.join") do
    n.times {
      "Stackoverflow is awesome!".chars.map.with_index {|c,i| i%2==0 ? c.upcase : c.downcase}.join
    }
  end
end

# $ ruby benchmark_downcase_vs_enum_downcase.rb
# Rehearsal -----------------------------------------------------------------------------------------------------------
# String#downcase.chars.map.with_index {|c,i| i%2==0 ? c.upcase : c}.join  10.750000   0.030000  10.780000 ( 10.801773)
# String#chars.map.with_index {|c,i| i%2==0 ? c.upcase : c.downcase}.join  11.580000   0.020000  11.600000 ( 11.635031)
# ------------------------------------------------------------------------------------------------- total: 22.380000sec
#
#                                                                              user     system      total        real
# String#downcase.chars.map.with_index {|c,i| i%2==0 ? c.upcase : c}.join  10.570000   0.030000  10.600000 ( 10.621634)
# String#chars.map.with_index {|c,i| i%2==0 ? c.upcase : c.downcase}.join  12.210000   0.070000  12.280000 ( 12.588328)