Adding benchmark script

benchmarks.rb

@@ -0,0 +1,19 @@
+$:.unshift(File.dirname(__FILE__) + '/lib')
+require 'rubygems'
+require 'logger'
+require 'delayed_job'
+require 'benchmark'
+
+Delayed::Worker.logger = Logger.new('/dev/null')
+
+Benchmark.bm(10) do |x|
+  [:active_record, :mongo_mapper, :data_mapper].each do |backend|
+    require "spec/setup/#{backend}"
+    Delayed::Worker.backend = backend
+
+    n = 10000
+    n.times { "foo".send_later :length }
+
+    x.report(backend.to_s) { Delayed::Worker.new(:quiet => true).work_off(n) }
+  end  
+end