もう一個面白かったやつ
irb(main):007:0> require 'benchmark' => true irb(main):008:0> require 'bigdecimal' => true irb(main):009:0> n = 1000 => 1000 irb(main):011:0> Benchmark.realtime { n.times { BigDecimal('3') == true } } => 0.023832 irb(main):010:0> Benchmark.realtime { n.times { BigDecimal('3').is_a?(TrueClass) } } => 0.001259
https://github.com/rails/rails/commit/1fd78305b5812c186d9eed9475677f90946eba5f