03 / Experience
This page defines 15 Site Performance & Rendering terms. Each entry gives a plain definition, a What to check step you can apply to your own site, and links to deeper SiteAuditLint guides where they exist.
HTTPS
HTTPS is the secure version of HTTP, encrypting data between the browser and the server. Google uses HTTPS as a lightweight ranking signal.
HTTP URLs redirect to HTTPS in one hop, certificates are valid, and pages load no mixed content.
Go deeper: Not HTTPS issue, HTTPS pages linking to HTTP
Mobile-friendly
A mobile-friendly page is easy to read and use on a smartphone, with readable text, tappable buttons, and no horizontal scrolling.
Test key templates on real mobile devices, since Google indexes the mobile version of your pages.
Go deeper: Missing viewport issue
Page speed
Page speed describes how quickly a page loads and becomes usable. Google measures it mainly through Core Web Vitals.
Use field data from real users, not only lab scores, to judge whether speed is actually a problem.
Core Web Vitals
Core Web Vitals are three Google metrics measuring real-user page experience: Largest Contentful Paint for loading, Interaction to Next Paint for responsiveness, and Cumulative Layout Shift for visual stability.
Review the Core Web Vitals report in Search Console by URL group, and fix the templates with the most poor URLs first.
Are Core Web Vitals a ranking factor?
Yes, as part of page experience, but Google describes them as one signal among many. Relevance and content quality matter more.
Largest Contentful Paint (LCP)
Largest Contentful Paint measures how long the largest visible element, often a hero image or heading, takes to render. A good LCP is 2.5 seconds or less.
The LCP image is not lazy-loaded, is properly sized, and loads early with a fetch priority hint.
Interaction to Next Paint (INP)
Interaction to Next Paint measures how quickly a page responds visually to user interactions such as clicks and taps. A good INP is 200 milliseconds or less. INP replaced First Input Delay in March 2024.
Identify long JavaScript tasks and heavy third-party scripts that block the main thread.
Cumulative Layout Shift (CLS)
Cumulative Layout Shift measures how much visible content moves unexpectedly while a page loads. A good CLS score is 0.1 or less.
Images, ads, and embeds have reserved dimensions, and web fonts do not cause large text shifts.
Time to First Byte (TTFB)
Time to First Byte is the time between a browser requesting a page and receiving the first byte of the response. A slow TTFB delays every other loading metric.
Monitor server response times, caching, and CDN coverage, especially for uncached pages.
Go deeper: Slow response issue
Mobile-first indexing
Mobile-first indexing means Google primarily uses the mobile version of a page's content for indexing and ranking.
The mobile version has the same content, structured data, headings, and links as the desktop version.
Rendering
Rendering is the process of executing a page's HTML, CSS, and JavaScript to produce the final page that users and search engines see.
Compare the raw HTML with the rendered HTML to confirm key content and links do not depend on failed scripts.
Go deeper: Rendering
Client-side rendering
Client-side rendering builds page content in the browser with JavaScript after the initial HTML loads. Search engines must render the JavaScript to see the content.
Critical content, links, titles, and canonicals appear in the rendered HTML in the URL Inspection tool.
Go deeper: JavaScript rendering in SiteAuditLint
Server-side rendering
Server-side rendering generates the full HTML on the server before sending it to the browser, so content is visible without running JavaScript first.
Server-rendered and hydrated versions match, and no content or metadata changes after JavaScript runs.
Is server-side rendering better for SEO?
Generally, yes. It makes content immediately available to every crawler, including AI crawlers that often do not run JavaScript.
Dynamic rendering
Dynamic rendering serves pre-rendered HTML to bots and client-side rendered pages to users. Google now describes it as a workaround rather than a recommended long-term solution.
If you still use it, make sure bots and users receive equivalent content to avoid cloaking issues.
Go deeper: Dynamic content
JavaScript SEO
JavaScript SEO is the practice of making JavaScript-heavy sites crawlable, renderable, and indexable by search engines.
Links use real href attributes, content does not require user interaction to load, and important pages are not rendered only after delays.
Go deeper: JavaScript SEO course, JavaScript SEO checklist
Edge SEO
Edge SEO is making SEO changes at the CDN or edge level, such as redirects, headers, or HTML edits, without changing the origin codebase.
Document every edge rule, since changes made outside the codebase are easy to forget during later releases.
Browse the full SEO terms glossary, or run a technical SEO audit with SiteAuditLint to check these signals on your own site.