Code bogging down

I have a class called codeCreator that creates a long string and stores it in its property codeCreator.outputString. Each time I need the string, I instantiate the class, copy outputString into an xmlNode, and then delete the object…

var q:codeCreator = new codeCreator();
q.create();
var node:XMLNode = new XMLNode(3,q.outputString);
delete q;

but each time I do this, it runs a bit slower. Am I not cleaning up properly?? It runs like a charm the first time, then it’s downhill from there.