Speedup applications boot by caching file locations during require calls.

Speed gain depends on your number of gems. Under 100 gems you likely won't see the difference, but for bigger applications it can save 1 to 3 seconds of boot time per 100 used gems.

# Gemfile
gem 'bootscale', require: false

For correctness cache should be updated everytime $LOAD_PATH is modified by calling Bootscale.regenerate.

For Rails apps it means adding an initializer in config/application.rb.

module MyApp
  class Application < Rails::Application
    initializer :regenerate_require_cache, before: :load_environment_config do
      Bootscale.regenerate
    end
  end
end

Locate require 'bundler/setup' in config/boot.rb and add require 'bootscale/rails' after it:

require 'bundler/setup'
require 'bootscale/rails'

Locate require 'bundler/setup', and add require 'bootscale/setup' after it:

require 'bundler/setup'
require 'bootscale/setup'

In order to gain ~10-30ms of extra load speed, you can use the msgpack gem:

# Gemfile
gem 'msgpack',   require: false
gem 'bootscale', require: false

# config/boot.rb (or wherever you have the require of bundler/setup)
require 'bundler/setup'
require 'msgpack'
require 'bootscale/setup' # or require 'bootscale/rails'

Bootscale caches the absolute location of all requirable files on the $LOAD_PATH and patches require + autoload to use these absolute paths, thereby avoiding having to check all load paths for every require.

Problem outlined in this talk

If you're experiencing problems with loading your application, especially after moving files around, try deleting the tmp/bootscale folder.

Bug reports and pull requests are welcome on GitHub at https://github.com/byroot/bootscale.

Local development: your load time will be very slow when using a local copy for development like gem 'bootscale', path: '~/Code/bootscal', use via git instead.

Thanks to Aaron Patterson for the idea of converting relative paths to absolute paths.