Constant Global object on a Ruby on Rails server
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Working with Rails 3.2.1 and Ruby 1.9.3, where is the proper place to initialize a Global constant object such that it is only initialized once when the rails server is started. 

Right now I am declaring it as instance object as and it is initialized every time the method is called: 

    @object_wanted_to_be_global_const = Gemname::GemnameClass.new 'input'
    

Where is the best place to declare this as a global constant variable?

If declared as a global instead of an instance, how will this affect performance as the variable is accessed on almost every request?