gistfile1.txt

require 'benchmark/ips'

class Foo
  define_method("foo") { }
  class_eval 'def bar; end'

  def inline_foo
    foo
    foo
    foo
    foo
    foo
  end

  def inline_bar
    bar
    bar
    bar
    bar
    bar
  end
end

Benchmark.ips do |x|
  foo = Foo.new
  x.report("class_eval") { foo.inline_bar }
  x.report("define_method") { foo.inline_foo }
end

          class_eval  6801365.4 (±1.1%) i/s -   34000866 in   4.999752s (cycle=203598)
       define_method  4382386.9 (±2.1%) i/s -   21982388 in   5.018583s (cycle=238939)