Thank you for your replies. I would understand from this that if it is possible from a design and maintenance viewpoint it is better in terms of operational speed to create famlies of classes. In other words, if I have several types of customers (cash customers, financed in house customers, sweetheart deals with finance company customers etc) I could create one family of classes to handle the creation and saving of customers and another family to handle payments, accounts receivable etc. This would split the code up and allow faster loading and execution. I am obviously new to this and I just worry that I will go overboard and really slow down the app. Should I be concerned?