Speed & Core Web Vitals
The metrics Google measures on real visitors, what slows a page down and how to make it fast.
Guides
- Speed12 min read
CDN basics: what a CDN fixes and what it does not
A CDN puts copies of your files near your visitors and takes TLS, HTTP/2 and compression off your server. What that changes, what it cannot, and how to set one up without caching the wrong pages.Updated 25 Sept 2026 - Speed13 min read
Core Web Vitals for e-commerce: product and category pages
Where shops fail LCP, CLS and INP on product pages, category grids and checkout, with the fix for each template, the WooCommerce and Shopify settings behind them, and how to measure per template.Updated 25 Sept 2026 - Speed14 min read
Core Web Vitals for news and publisher sites: ads, embeds and CLS
Publishers fail Core Web Vitals their own way: unreserved ad slots, banners that push content, embeds that resize, ad tech on the main thread. The fix for each, with code and a per-template checklist.Updated 25 Sept 2026 - Speed8 min read
Core Web Vitals for site owners — LCP, INP and CLS without jargon
Google measures three things about how a page feels: how fast the main content shows up, how quickly it reacts to taps, and whether it jumps around. This guide explains each in plain terms, what "good" means, where the numbers come from, and the usual cause behind each failing one.Updated 25 Sept 2026 - Speed13 min read
Core Web Vitals history: reading 40 weeks of real-user data
A speed test shows how a page performs today. Forty weeks of Chrome UX Report data show when it changed, so you can find the update, plugin or image behind a drop and know when a fix has landed.Updated 25 Sept 2026 - Speed13 min read
Critical CSS: is it still worth doing in 2026?
Critical CSS inlines the styles for the first screen and loads the rest later. Learn when it still pays, what it costs to maintain, the simpler fixes to try first and how to measure the difference.Updated 25 Sept 2026 - Speed12 min read
DOM size: why 3,000 nodes is a problem and how to shrink a page
A page with thousands of HTML elements is slow to style, lay out and react to taps. Find where the nodes come from, count them yourself, and cut them with builder settings and content-visibility.Updated 25 Sept 2026 - Speed13 min read
Field data vs lab data: why PageSpeed and Search Console disagree
Lab data is one throttled test run; field data is 28 days of real Chrome visitors. Why the two disagree, which one Google ranks with, and what to do in each of the four combinations.Updated 25 Sept 2026 - Speed14 min read
Fonts: system stack vs web font, the honest trade-off
A web font costs 100–300 KB, a blocking stylesheet and a layout shift; a system stack costs brand consistency. Measure both on your page, see what moves in FCP, LCP and CLS, and pick with numbers.Updated 25 Sept 2026 - Speed11 min read
How to fix Cumulative Layout Shift (CLS): images, fonts, ads, embeds
Find the element that makes your page jump, then reserve its space with width and height, aspect-ratio or a min-height slot. Covers images, ads, embeds, banners and web fonts, with code.Updated 25 Sept 2026 - Speed12 min read
How to fix Interaction to Next Paint (INP) and slow taps
INP measures how long your page takes to react to a tap or click. Learn what makes it slow, how to find the interaction at fault, and fix it by breaking up long tasks and trimming scripts.Updated 25 Sept 2026 - Speed13 min read
How to fix Largest Contentful Paint (LCP), step by step
Find the element that decides your LCP, see which of its four parts is slow, and fix them in the order that pays off most, from preloading the hero to a faster server. With HTML and WordPress code.Updated 25 Sept 2026 - Speed9 min read
How to read a website speed test
A speed test returns a score, five metrics and a list of opportunities. This guide explains what each number means for a visitor, which ones Google uses for ranking, why the same page scores differently on every run, and how to turn the list into three fixes that matter.Updated 25 Sept 2026 - Speed7 min read
HTTP/2 and HTTP/3 — what they change and how to turn them on
HTTP/1.1 loads six files at a time and queues the rest. HTTP/2 sends them all over one connection; HTTP/3 removes the slow handshake. This guide tests which one your site negotiates and shows the one-line change on each host, server and CDN.Updated 25 Sept 2026 - Speed14 min read
Image CDNs and on-the-fly resizing: URL parameter or build step?
An image CDN resizes and converts to WebP or AVIF from a URL parameter, so one master serves every screen. What the services cost, the URL patterns, the pitfalls, and when a build step is enough.Updated 25 Sept 2026 - Speed8 min read
Image sizes that do not hurt — a practical guide
Images are most of the bytes on most pages. Find the 2 MB hero, the 1600-pixel thumbnail and the images with no width and height, then fix them with the right export size, format and attributes, on any CMS.Updated 25 Sept 2026 - Speed10 min read
Lazy loading images and iframes done right (without hurting LCP)
Lazy loading saves bandwidth on long pages, but on the wrong image it makes LCP slower. Learn what to lazy-load, what never to, why dimensions matter, and how WordPress and plugins handle it for you.Updated 25 Sept 2026 - Speed11 min read
Lighthouse score vs Core Web Vitals: why 100 does not mean fast
The Lighthouse score is one simulated lab run; Core Web Vitals are what real visitors experienced over 28 days. Learn why they disagree, which one Google uses and which one to work on first.Updated 25 Sept 2026 - Speed12 min read
Long tasks and main-thread work: the JavaScript diet
A task over 50 ms freezes the page for that long. How long tasks become Total Blocking Time and a poor INP, how to find the scripts behind them, and how to remove, defer, split and offload the work.Updated 25 Sept 2026 - Speed13 min read
Mobile vs desktop scores: why mobile is always lower and what to do
The same page scores 95 on desktop and 55 on mobile because the mobile test simulates a slow phone on a slow network. What is simulated, why Google uses the mobile number, and what to fix first.Updated 25 Sept 2026 - Speed11 min read
Modern image formats: WebP, AVIF and when JPEG is still fine
Cut image bytes by a quarter to a half with WebP and AVIF without a visible change: which format for which image, the quality settings that work, the picture fallback and CMS auto-conversion.Updated 25 Sept 2026 - Speed12 min read
Preload, preconnect, prefetch: which resource hint when
Resource hints tell the browser what to fetch before it would find out on its own. One hint per job, the exact syntax for images, fonts and scripts, and the mistakes that make hints slower than none.Updated 25 Sept 2026 - Speed14 min read
Reading a filmstrip: where the seconds go before the page looks ready
A filmstrip shows what the visitor saw at each moment of the load. Learn to match its frames to FCP, LCP, Speed Index and CLS, recognise the five typical stories, and know what to change for each.Updated 25 Sept 2026 - Speed14 min read
Reading a waterfall chart: what each bar tells you
A request waterfall shows every file a page loads and when. Learn the anatomy of a bar, the six patterns behind most slow pages, how to read priority and initiator, and what to fix in which order.Updated 25 Sept 2026 - Speed12 min read
Render-blocking resources: the CSS and JS that delay the first paint
Find the stylesheets and scripts that keep your page blank, then defer, inline, split or remove them in the right order, with fixes for HTML, WordPress and Shopify.Updated 25 Sept 2026 - Speed13 min read
Responsive images: srcset and sizes explained with real numbers
Stop sending a 2000-pixel photo to a 400-pixel slot. How the browser picks from srcset, why sizes is required, and a three-breakpoint example with the real pixel counts, on any CMS.Updated 25 Sept 2026 - Speed13 min read
Server response time on shared hosting: options that cost nothing
A slow first byte on a €5 hosting plan is usually PHP, plugins and a missing cache, not the plan. The fixes that cost nothing, in the order that pays off, and when it really is time to move.Updated 25 Sept 2026 - Speed12 min read
Service workers and offline pages: the minimal safe version
A service worker does nothing for a first visit and can serve stale pages for weeks. The minimal recipe: network-first HTML, cached hashed assets, an offline page, a kill switch, and when to skip it.Updated 25 Sept 2026 - Speed14 min read
Speed budgets: setting one and holding to it in CI
Pick a speed budget from your own numbers, write it into the repo and make the build fail when a pull request breaks it, with Lighthouse CI configs and a budgets.json for a shop and a marketing site.Updated 25 Sept 2026 - Speed13 min read
Speed Index and First Contentful Paint: what moves them
FCP is the first pixel of content, Speed Index is how quickly the screen fills up. Learn what each measures, why both are lab-only, how they relate to LCP, and which fixes move them on a real site.Updated 25 Sept 2026 - Speed12 min read
Third-party scripts: taming tag managers, chat widgets and ads
Measure what tag managers, chat widgets, pixels and embeds cost your visitors, then cut it with removal, facades, consent-gated loading and tag manager hygiene, with a budget you can hold to.Updated 25 Sept 2026 - Speed9 min read
TTFB — what a slow server looks like and what to do about it
Time to First Byte is the wait before anything at all arrives from your server. Over 800 ms and every other metric suffers. This guide shows how to measure it properly, tells DNS, connection and server time apart, and lists the fixes that cost nothing on shared hosting and WordPress.Updated 25 Sept 2026 - Speed13 min read
Video on landing pages without killing your LCP
Hero videos and YouTube embeds are the fastest way to a 6-second LCP. Learn what counts as the LCP element for video, the poster and facade patterns that keep it under 2.5 s, plus WordPress settings.Updated 25 Sept 2026 - Speed13 min read
Web fonts without layout shift: font-display, preload and subsetting
Stop headings from flashing blank or jumping when a web font arrives. Pick the right font-display value, preload the two fonts above the fold, subset them and tune the fallback metrics.Updated 25 Sept 2026
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