Image Optimization and WebP Basics — Why WebP Is Smaller, and How Browsers Decide to Use It

It's often cited that the biggest drag on WordPress page speed isn't code at all — it's images. The same-looking photo can end up dramatically smaller in file size depending on whether it stays as JPEG/PNG or gets converted to WebP. This post looks at why WebP tends to be lighter, how browsers negotiate which format to load, and how WordPress itself has adopted the format over time. JPEG, standardized back in 1992, is built on discrete cosine transform (DCT) compression. WebP, introduced by Google in 2010, takes a different route: it repurposes the intra-frame compression techniques from the V