In Listbox ROD, when get another partial part of model in the listbox, the mechanism is clear all the item in listbox in first round and render all of the part of item in second round. The defect of the mechanism is when doing rod, the second round of rendering may has lots of repeated part comparing with first round of rendering with a high possibility. it takes a lot cost when rendering every item in the listbox. So rather only clearing the non-repeated items is more efficient before we get into the second round of rendering.