This doesn&#x27;t surprise me. The PageSpeed Insights site has a very atypical use case.<p>Anyway, the PSI &#x27;score&#x27; is only a rough guide to help point you to problems. It can be kind of useful, in that if you get something like 97-100 then you can be pretty sure it&#x27;s a very fast page... but it&#x27;s also probably a page that doesn&#x27;t do much beyond displaying something. With a more serious web app that does more interesting things, the score becomes a less useful indicator – it&#x27;s often possible to make code changes that improve perceived performance but actually reduce the PSI score.<p>For example, it&#x27;s impossible for PSI to really know if inlining a script is going to generally improve or worsen performance, because it doesn&#x27;t know your site&#x27;s usage patterns, or which parts of your UI need to render first for a user to feel that the your UI &#x27;is fast&#x27;, whatever that means. UI performance is a subtler art than, say, algorithmic performance, and much less quantifiable. That&#x27;s why many people prefer webpagetest.org, which comes with much smarter tools to record and analyse <i>how</i> the page loads, so you can actually improve UI performance.