从一堆模型对象生成XML时速度较慢

class GenericFormatter < Formatter
 attr_accessor :tag_name,:objects

 def generate_xml
   builder = Nokogiri::XML::Builder.new do |xml|
   xml.send(tag_name.pluralize) {
   objects.each do |obj|
        xml.send(tag_name.singularize){

            self.generate_obj_row obj,xml
        }                
    end
    }
   end
   builder.to_xml
 end


def initialize tag_name,objects
  self.tag_name = tag_name
  self.objects = objects
end


def generate_obj_row obj,xml
   obj.attributes.except("updated_at").map do |key,value|
     xml.send(key, value)
   end
   xml.updated_at obj.updated_at.try(:strftime,"%m/%d/%Y %H:%M:%S") if obj.attributes.key?('updated_at')
end
 end 
class GenericFormatter < Formatter
 attr_access