One more pitfall: if you add or remove elements, it also causes a reflow. A common pitfall with applications that render lists is that they do append operations

One more pitfall: if you add or remove elements, it also causes a reflow. A common pitfall with applications that render lists is that they do append operations iteratively (with a reflow for each iteration) rather than in one go (with only one reflow). http://jankfree.org/ http://jankfree.org/ is a good resource for causes of slowdown.