How can a theme author ensure their theme adheres to best performance practices?

Optimizing all images for the web is crucial for a theme author's best performance practices. High-resolution images can significantly slow down website loading times, which can negatively impact user experience and SEO. By compressing images and using appropriate formats (like WebP or JPEG for photographs and PNG for graphics), a theme can load faster, leading to better performance on various devices. This optimization ensures that images are not only visually appealing but also lightweight, enhancing the overall speed of the theme.

Use of inline CSS is not recommended universally since it can increase page size and limit caching benefits. Avoiding JavaScript entirely would likely hinder functionality and interactivity, which are important aspects of modern web design. Relying solely on external stylesheets might lead to issues if not handled properly, such as increased HTTP requests if not optimized for loading. Optimizing images, therefore, stands out as a straightforward and effective method for improving loading times and overall theme performance.