I'm facing the same problem, a lag while scrolling table view. I have a tableview-cell in which I've embedded a vertical collection view. I'm also downloading and downsampling the images in the background thread still there is a lag in scrolling. After going through my code I figured out that the collection view cells are not being dequeued as the table view scrolls instead they are kept in memory until the parent tableView-cell is dequeued. I'm looking for ways to improve my code. It would be a great help if someone can point me in the right direction.