constants.rb

require 'benchmark'

OK = "OK".freeze
Ok = "OK".freeze

Benchmark.bm(30) do |b|
  b.report('upcase constant') do
    5_000_000.times { 'OK' == OK }
  end

  b.report('camel case constant') do
    5_000_000.times { 'OK' == Ok }
  end
end

__END__
                                    user     system      total        real
upcase constant                 2.020000   0.010000   2.030000 (  2.039640)
camel case constant             2.040000   0.010000   2.050000 (  2.057488)