Retained Display Lists for improved page performance

Display list building is the process in which we collect the set of high-level items to display on screen (borders, backgrounds, text and much more), and then sort the list, according to CSS painting rules, into the correct back-to-front order. By retaining the display list and only reloading the assets that have changed since first paint, we are able to optimize painting performance especially for highly interactive pages. Look for this feature in this week’s release of Firefox 61.