Comparing codepoints is faster it seems

codepoint_bench.rb

require 'benchmark/ips'

def _codepoint(text)
  text.each_codepoint do |p|
    case p
    when 97 then 97
    when 98 then 98
    when 99 then 99
    when 100 then 100
    when 101 then 101
    when 102 then 102
    when 103 then 103
    when 104 then 104
    when 105 then 105
    when 106 then 106
    when 107 then 107
    when 108 then 108
    when 109 then 109
    when 110 then 110
    when 111 then 111
    when 112 then 112
    when 113 then 113
    when 114 then 114
    when 115 then 115
    when 116 then 116
    when 117 then 117
    when 118 then 118
    when 119 then 119
    when 120 then 120
    when 121 then 121
    when 122 then 122
    end
  end
end

def _char(text)
  text.each_char do |c|
    case c
    when "a" then 97
    when "b" then 98
    when "c" then 99
    when "d" then 100
    when "e" then 101
    when "f" then 102
    when "g" then 103
    when "h" then 104
    when "i" then 105
    when "j" then 106
    when "k" then 107
    when "l" then 108
    when "m" then 109
    when "n" then 110
    when "o" then 111
    when "p" then 112
    when "q" then 113
    when "r" then 114
    when "s" then 115
    when "t" then 116
    when "u" then 117
    when "v" then 118
    when "w" then 119
    when "x" then 120
    when "y" then 121
    when "z" then 122
    end
  end
end

text = %Q{ Contrary to popular belief, Lorem Ipsum is not simply random text.
It has roots in a piece of classical Latin literature from 45 BC, making it
over 2000 years old. Richard McClintock, a Latin professor at Hampden-Sydney
College in Virginia, looked up one of the more obscure Latin words,
consectetur, from a Lorem Ipsum passage, and going through the cites of the
word in classical literature, discovered the undoubtable source. Lorem Ipsum
comes from sections 1.10.32 and 1.10.33 of de Finibus Bonorum et Malorum (The
Extremes of Good and Evil) by Cicero, written in 45 BC.  This book is a
treatise on the theory of ethics, very popular during the Renaissance.  The
first line of Lorem Ipsum, "Lorem ipsum dolor sit amet..", comes from a line in
section 1.10.32.

The standard chunk of Lorem Ipsum used since the 1500s is reproduced below for
those interested. Sections 1.10.32 and 1.10.33 from "de Finibus Bonorum et
Malorum" by Cicero are also reproduced in their exact original form,
accompanied by English versions from the 1914 translation by H. Rackham. }

Benchmark.ips do |x|
  x.report("codepoint")  { _codepoint(text) }
  x.report("char")       { _char(text) }
  x.compare!
end

results.txt

Calculating -------------------------------------
           codepoint     1.150k i/100ms
                char   486.000  i/100ms
-------------------------------------------------
           codepoint     11.751k (± 2.1%) i/s -     59.800k
                char      4.967k (± 1.7%) i/s -     25.272k

Comparison:
           codepoint:    11751.1 i/s
                char:     4966.7 i/s - 2.37x slower