Which technical term refers to the percentage of elements that remain unloaded at specific points in time?

The term that refers to the percentage of elements that remain unloaded at specific points in time is the Speed Index. This metric measures how quickly the contents of a page are visually populated during the loading process. It quantifies the time it takes for visible parts of a web page to be displayed, which is crucial for assessing user experience. A lower Speed Index indicates that most elements are loading quickly, while a higher value implies that many elements remain unloaded, which can lead to a perception of sluggish performance.

In contrast, load time generally pertains to the total time taken for a page to load fully rather than the specific percentage of elements that are still unloaded at any point. User action duration focuses on the time a user spends interacting with a web application or page, without specifically addressing the loading of elements. Data retention refers to how long certain data is stored, which is unrelated to the loading performance of web elements.