Speed testing is one of the most significant tasks you undertake, as it can tell you just how nippy your site is for end users. A slow site can be a disaster for your user experience (UX). However, the JavaScript and CSS your site loads can have a big impact, so it’s one of the first aspects you’ll look at. Google Lighthouse focuses more on the experience of the user, and its ‘eliminate render blocking resources’ opportunity lets you handle one key element of a fast page speed.