Speed up assets:precompile with Rails 3.1/3.2 Capistrano deployment

Question

My deployments are slow, they take at least 3 minutes. The slow Capistrano task during deploy is assets:precompile. This takes probably 99% of the total deploy time. How can

Answer 1

tommasop's solution doesn't work when enabled cached-copy, my modified version:

task :precompile, :roles => :web, :except => { :no_release => true } do
  from = source.next_revision(current_revision)
  if capture("cd #{shared_path}/cached-copy && git diff #{from}.. --stat | grep 'app/assets' | wc -l").to_i > 0
    run %Q{cd #{latest_release} && #{rake} RAILS_ENV=#{Rubber.env} #{asset_env} assets:precompile:primary}
  else
    logger.info "Skipping asset pre-compilation because there were no asset changes"
  end
end