The Listmodel is not efficient enough

I need a list with such feature 1. The data background should be dynamic increase from from the bottom 2. The items in view should be grouped by category 3. The group title item could be expanded/collapsed to show/disappear the items 4. The highlighted item could be adjust when expanded/collapsed occurs I used javascript code to be the engine to update the data model of ListModel object. It could be very fast at the very beginning, however when the data about exceed 600, it always costs about 1 second on my device(An CortexA8 device). At that period, I nearly could not move my mouse at all.