What are the most common performance issues in business websites?

The most common performance issues in business websites are unoptimized images (served in JPEG or PNG format at desktop resolution regardless of the requesting device, without WebP conversion or lazy loading), render-blocking JavaScript and CSS that delay the browser from displaying page content, and excessive third-party scripts (chat widgets, analytics tags, advertising pixels, and social media embeds) that add significant load time and reduce Interaction to Next Paint scores.

Server-side issues include slow TTFB caused by unoptimized database queries, absence of server-side caching, or hosting on shared infrastructure with insufficient resources for the site’s traffic volume. Font loading without font-display: swap causes invisible text during load (FOIT), contributing to poor perceived performance. Each of these issues is identifiable through a Lighthouse audit or WebPageTest analysis and addressable without a full site rebuild in most cases.