Potentially faster boot

application.rb

# THANKS EVERYONE FOR YOUR BELOVED BENCHMARKS.
# THIS PATCH IS NOW IN RAILS:
#
# https://github.com/rails/rails/commit/885a599303585b796da7a0a1c3ccd0bc5c642134 

# Please add the following lines after Bundler.require
# and before "class Application < Rails::Application"
# in your config/application.rb
#
# Notice this is just an experiment, don't leave those
# lines there after the experiment. Then please benchmark
# your app boot time in development before and after adding
# those lines. A simple benchmark is:
#
#   time script/rails runner "MODEL"
#
# Where MODEL is a model available in your app. Also,
# please run the command above at least three times to
# ensure we don't have fake samples. :)
#
# Please post the results in the comments below of the
# benchmarks before and after adding the code. <3
#
# This patch should work on Rails 3.0, 3.1 and master.
#
# Extra: if you could run your app in development and
# production (in your machine!!) with this patch on
# for a couple minutes and report any errors, you will
# win extra <3 <3 <3.

require "active_support/dependencies"

ActiveSupport::Dependencies::WatchStack.class_eval do
  def watching?
    !@watching.empty?
  end
end

def load_dependency(file)
  if ActiveSupport::Dependencies.load? && ActiveSupport::Dependencies.constant_watch_stack.watching?
    ActiveSupport::Dependencies.new_constants_in(Object) { yield }
  else
    yield
  end
rescue Exception => exception  # errors from loading file
  exception.blame_file! file
  raise
end

Thanks everyone for your beloved benchmarks. This patch is now in Rails:

rails/rails@885a599