A simple way to have a rough idea of where the time is spent for Ruby require

investigate_ruby_requires.rb

$requires_index = {}

if true
    # Override the require method to track load times
  def custom_require(file)
    starting = Process.clock_gettime(Process::CLOCK_MONOTONIC)
    
    result   = original_require(file)
    
    ending   = Process.clock_gettime(Process::CLOCK_MONOTONIC)
    elapsed = ending - starting

    $requires_index[file] ||= {:count => 0, :elapsed => 0.0}
    $requires_index[file][:count] += 1
    $requires_index[file][:elapsed] += elapsed

    if elapsed >= 0.01
      puts "Required #{file} in #{elapsed} seconds"
    end
    result
  end

  # Replace the original 'require' method with our custom implementation
  alias original_require require
  alias require custom_require
end