Is PageSpeed Insights enough for a site audit?

What to do about it

1. Open PageSpeed Insights and read the field data first. Google classes LCP as good at 2.5 seconds or less, INP at 200 milliseconds or less, and CLS at 0.1 or less, at the 75th percentile.
2. If you are only checking a deploy or a before-and-after change, stay on PageSpeed Insights. The score is the measurement.
3. If the score is poor and you do not know which Squarespace, Wix, or Shopify setting to change, the score is not the plan.
4. Run the free WebVitalist scan on the same URL. It checks the public HTML and names the technical issues on that page.
5. When you want Lighthouse plus a prioritized plan, buy a one-time Deep Audit. You do not need a monthly SEO suite for that single checkup.

What WebVitalist checks

The free scan runs 19 technical checks on one public URL. These are the ones that matter for this question:

• Server response time (ttfb): The free scan records how long the server took to deliver the HTML and warns when that took longer than 1,500 ms.
• HTML size (html-size): The free scan warns when the HTML document is larger than 400 kB, which the browser must download and parse before it can paint anything.
• Mobile viewport (viewport): Google assesses Core Web Vitals on mobile. The free scan fails a page whose viewport meta tag is missing, because without it a phone renders the desktop layout.

A paid audit ($9 and up) also runs a real mobile Lighthouse test through Google PageSpeed Insights and reads field data for LCP, INP and CLS, where Google has it.