Experimental assets compilation before running test suite. However it does not give me any boost.

spec_assets.rb

# See https://github.com/teampoltergeist/poltergeist/issues/677#issuecomment-222919584
# https://dzone.com/articles/precompiling-rails-assets
RSpec.configure do |config|
  config.before :all do
    ENV['PRECOMPILE_ASSETS'] ||= begin
      case self.class.metadata[:type]
      when :feature, :view
        STDOUT.write "Precompiling assets..."

        require 'rake'
        Rails.application.load_tasks
        Rake::Task['assets:precompile'].invoke

        STDOUT.puts " done."
        Time.now.to_s
      end
    end
  end
end