Use presenter if the controller is full of instance variables. Memoize instance variables !

presenter.rb

# => config/application.rb
config.autoload_paths = %W(#{config.route}/presenters) # loading the file defining the presenter

#/app/presenters/tweets/show_presenter
module Tweets
  class ShowPresenter
    extend ActiveSupport::Memoizable # Module of class instance methods : memorize instante variables
    
    def initialize(tweet)
      @tweet = tweet
    end
  
    def username
      @tweet.user.username
    end
  
    def status
      @tweet.status
    end
    
    def favorites_count
      @tweet.favorites.count
    end
    
    memoize :username, :status, :favorites_count  # alternative => username ||= @tweet.user.username
  end
end

# Tweets controller
class TweetsController < ApplicationController
  include Tweets
  
  def show
    @presenter = ShowPresenter.new( Tweet.find(params[:id]) )
  end
end

#/app/views/tweets/show.html.erb
# => <%= @presenter.username.body %>
# => <%= @presenter.username.favorites_count %>