include files in mvc model php -

I am making my own MVC model, so I have to include all my models and controller class.

Every time I need a model in a controller, I use it:

  need_once ('myModel.php');   
 Import a little bit in Java  
 But I have a question, is there a good way to continue this way? I like to include all my models and controllers at the beginning of the code but I'm afraid the solution is very heavy.  
 Thanks   
 
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