Instrument bundler for gem load performance

runtime.rb

    def require(*groups)
      gem_load_times = {}
      groups.map! { |g| g.to_sym }
      groups = [:default] if groups.empty?

      @definition.dependencies.each do |dep|
        # Skip the dependency if it is not in any of the requested
        # groups
        next unless ((dep.groups & groups).any? && dep.current_platform?)

        required_file = nil

        begin
          # Loop through all the specified autorequires for the
          # dependency. If there are none, use the dependency's name
          # as the autorequire.
          start_dep_time = Time.now
          Array(dep.autorequire || dep.name).each do |file|
            required_file = file
            Kernel.require file
          end
        rescue LoadError => e
          REGEXPS.find { |r| r =~ e.message }
          raise if dep.autorequire || $1 != required_file
        ensure
          gem_load_times[dep.name] =  Time.now - start_dep_time
        end
      end
      puts "PRINTING OUT GEM LOAD TIMES"
      sorted = gem_load_times.sort_by { |name, duration| duration}
      total_time = 0.0
      sorted.each { |gem, duration| puts sprintf("%-25s | %5.3f", gem, duration); total_time += duration }
      puts "--------------------------------------"
      puts "Total Gem load time       | #{total_time}"
    end