This is the single biggest reason to convert. APNGs use very limited, old-school compression methods. For anything longer than a few frames or with complex color changes, APNG file sizes balloon quickly. WebM uses advanced video codecs VP9 that compress data highly efficiently between frames.
Because an APNG is treated by browsers as an image (<img> tag), it plays automatically and endlessly. You cannot easily pause, rewind, or stop it without complex JavaScript workarounds. Because WebM is a video format, it uses the HTML5 <video> tag. This gives you native, out-of-the-box control over, Play/Pause/Stop, Looping (or playing just once), Scrubbing (seeking to specific times) and Autoplay settings
One of the main reasons people use APNG over standard MP4 is because APNG supports a transparent background (alpha channel). Fortunately, WebM also supports transparency. If you encode a WebM using the VP8 or VP9 codec with alpha channel support, you can overlay your animation cleanly on top of other web elements, just like an APNG.
Converting an APNG (Animated Portable Network Graphics) to WebM is a smart optimization choice primarily because it drastically reduces file size without sacrificing noticeable visual quality. While APNGs are excellent for preserving lossless, full-color animations with sharp edges and alpha transparency, they use inefficient compression methods that often result in bloated files, which can significantly slow down website loading times and eat up bandwidth. By contrast, WebM utilizes highly efficient VP8 or VP9 video codecs designed specifically for the web, shrinking animations down to a fraction of their original APNG size while still supporting crucial features like alpha channel transparency. Ultimately, making this conversion ensures faster page loads, smoother playback across modern browsers, and a substantially better overall user experience.