var Test = new Class({
    'Aspect':'We want to cancel this method execution',
    this_method_is_heavy_and_turns_out_to_be_not_required:function(){
        //for(i=0,max=1000000000;i<max;i++) ...
        alert("This Method is as useful as using confetti to clean your ass.")
    }
});
    
    
    
    
    var a = new Test();
  

    AOP.addEvent('pre', function(e){
   
    //Here you see how you can use regex to filter the methods to hijack
    if(/not_required$/.test(e.name)){
        e.cancel=true;
    }
    })

  a.this_method_is_heavy_and_turns_out_to_be_not_required();

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jsFiddle