Cache url_options on a per-request basis.

actionpack/lib/action_controller/metal/url_for.rb

@@ -5,16 +5,18 @@ module UrlFor
     include AbstractController::UrlFor
 
     def url_options
-      options = {}
-      if _routes.equal?(env["action_dispatch.routes"])
-        options[:script_name] = request.script_name.dup
-      end
+      @_url_options ||= begin
+        options = {}
+        if _routes.equal?(env["action_dispatch.routes"])
+          options[:script_name] = request.script_name.dup
+        end
 
-      super.merge(options).reverse_merge(
-        :host => request.host_with_port,
-        :protocol => request.protocol,
-        :_path_segments => request.symbolized_path_parameters
-      )
+        super.merge(options).reverse_merge(
+          :host => request.host_with_port,
+          :protocol => request.protocol,
+          :_path_segments => request.symbolized_path_parameters
+        ).freeze
+      end
     end
   end
 end