deploy.rb

namespace :deploy do
  namespace :assets do

    Rake::Task['deploy:assets:precompile'].clear_actions

    desc 'Precompile assets locally and upload to servers'
    task :precompile do
      on roles(fetch(:assets_roles)) do
        run_locally do
          with rails_env: fetch(:rails_env) do
            execute 'rm -rf public/assets'
            execute 'bin/rake assets:precompile'
            # Compress any non gz file
            execute 'find public/assets -type f|grep -v ".gz"|xargs gzip -f -9'
            # Delete any non gz file
            execute 'find public/assets -type f|grep -v ".gz"|xargs rm'
            # Pack everything in tar
            execute 'tar -cvvf assets.tar public/assets'
          end
        end

        within release_path do
          with rails_env: fetch(:rails_env) do
            # Upload the packaged tar (is faster than upload every file)
            upload!('assets.tar', ".")
            old_manifest_path = "#{shared_path}/public/assets/manifest*"
            execute :rm, old_manifest_path if test "[ -f #{old_manifest_path} ]"
            # Unpack tar
            execute "tar xvvf assets.tar -C #{shared_path}"
            # Create non gzip file versions
            execute "find #{shared_path}/public/assets -type f|grep '.gz'|xargs gunzip -f -k; echo Done"
            # Deletes package
            execute "rm assets.tar"
          end
        end

        run_locally { execute 'rm -rf public/assets' }
      end
    end

  end
end

Bassed in https://gist.github.com/andrey-skat/10399224