diff --git a/Rakefile b/Rakefile
index 2f0748e..afccabf 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,7 +1,8 @@
 require 'bundler/gem_tasks'
 require 'yaml'
+require 'benchmark'
 
-task :convert do
+file 'lib/data/US.yml' do
   codes = {}
   File.open('lib/data/US.txt').each_line do |line|
     array = line.split('\t')
@@ -16,3 +17,21 @@ task :convert do
     file.write codes.to_yaml
   end
 end
+
+file 'lib/data/US.marshal' => 'lib/data/US.yml' do
+  File.write('lib/data/US.marshal', Marshal.dump(YAML.load(File.read('lib/data/US.yml'))))
+end
+
+task :convert => ['lib/data/US.marshal', 'lib/data/US.yml']
+
+task :benchmark => :convert do
+  Benchmark.bm(15) do |x|
+    x.report("YAML.load") do
+      YAML.load(File.read('lib/data/US.yml'))
+    end
+
+    x.report("Marshal.load") do
+      Marshal.load(File.read('lib/data/US.marshal'))
+    end
+  end
+end
diff --git a/lib/data/US.marshal b/lib/data/US.marshal
new file mode 100644
index 0000000..4d87638
Binary files /dev/null and b/lib/data/US.marshal differ
diff --git a/lib/zip-codes.rb b/lib/zip-codes.rb
index 1791d4f..20643aa 100644
--- a/lib/zip-codes.rb
+++ b/lib/zip-codes.rb
@@ -1,5 +1,3 @@
-require 'yaml'
-
 module ZipCodes
   VERSION = '0.2.1'
 
@@ -11,8 +9,8 @@ def identify(code)
     def db
       @db ||= begin
         this_file = File.expand_path(File.dirname(__FILE__))
-        us_data = File.join(this_file, 'data', 'US.yml')
-        YAML.load(File.open(us_data))
+        us_data = File.join(this_file, 'data', 'US.marshal')
+        Marshal.load(File.open(us_data))
       end
     end