gistfile1.rb

require 'benchmark'

TIMES = 10_000_000

module M
  X = ''
  module N
    module A
      module B
        def self.x
          X
        end
      end
    end
  end
end

Benchmark.bm do |x|
  x.report("constant") { TIMES.times { ::M::N::A::B.x }}
  x.report("literal") { TIMES.times { '' }}
end

__END__
fxn@yeager:~/tmp $ ruby foo.rb
       user     system      total        real
constant  0.970000   0.000000   0.970000 (  0.974618)
literal  1.170000   0.010000   1.180000 (  1.173427)