When talking about performance in the context of frontend Web development, we can either mean network, computational, or rendering performance. In this section, we'll concentrate on rendering and computational performance, which are very tightly related.

First, let's draw parallels between a Web application and a video file, and between a browser and a video player. The biggest difference between the Web application running in the browser and the video file playing in the video player is that the web page needs to be generated dynamically, in contrast to the video which has been recorded, encoded, and distributed. However, in both cases, the user of the application sees a sequence of frames; the core difference is in how these frames are generated. In the world of video processing, when we play a video, we have it already recorded; it is the responsibility of the video decoder to extract the individual frames based on the compression algorithm. In contrast...