Вы можете добавить комментарий в начало / конец вашего application.html.erb?
# application_controller.rb
class ApplicationController < ActionController::Base
before_filter :set_start_timer
def set_start_timer
@start_time = Time.now
end
end
# application.html.haml
=@start_time # this is the overall processing time
=Time.now # this is the start view render time
=yield
=Time.now # this is the view render time after processing content