Rake::SprocketsTask custom rake task is still slow

[jricketson]

We have a lot of specs written in coffee that we compile to js before we run them. We do this with this code

  require 'rake/sprocketstask'
  require Rails.root.join  'lib/spec_sprockets'

  Rake::SprocketsTask.new :specs do |t|
    t.environment = SpecSprockets
    t.output      = Rails.root.join('public', 'spec')
    t.assets      = Dir.glob(Rails.root.join('spec', 'jasmine', '**', '*.*'))
    t.logger      = Logger.new($stdout)
    t.log_level   = :debug
    t.keep        = 1
  end

This task does not get any speed benefit from running your gem (it takes about 30s before and after your gem was included.) Do you have a recommended way of implementing this task?

Thanks