# File lib/nanoc/cli/commands/compile.rb, line 150
      def start
        Nanoc::NotificationCenter.on(:filtering_started) do |rep, filter_name|
          @filter_times[filter_name] ||= []
          @filter_times[filter_name] << Time.now
        end
        Nanoc::NotificationCenter.on(:filtering_ended) do |rep, filter_name|
          @filter_times[filter_name] << Time.now - @filter_times[filter_name].pop
        end
      end