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In-depth guides
Longer walkthroughs for specific setups: real screenshots, code you can paste and the reason behind every step. The short fix page for each check lives under Learn.
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52 guides, page 1 of 5.
- Speed13 min read
PageSpeed score: how to read it and what counts as good
A PageSpeed score is a 0-100 summary of five lab metrics from one simulated visit on a phone: 90 or more is good, 50-89 needs improvement, under 50 is poor. Here is what the number means, why it moves and what to fix first.Updated 15 Oct 2026 - Speed16 min read
Reading a waterfall chart and filmstrip: where the seconds go
A request waterfall shows every file a page loads and when; the filmstrip shows what the visitor saw meanwhile. Learn the anatomy of a bar, the six patterns behind most slow pages, how to match frames to metrics, and what to fix first.Updated 15 Oct 2026 - Speed14 min read
HTTP/2 vs HTTP/1.1: multiplexing, header compression and what changes for your site
HTTP/2 vs HTTP/1.1: HTTP/2 sends every file of a page over one connection at once and compresses headers, where HTTP/1.1 queues files six at a time. What changes, what does not, and what happened to server push.Updated 4 Oct 2026 - Speed12 min read
PNG vs JPG (JPEG): which to use for photos, graphics and transparency
PNG vs JPG comes down to the picture: JPG (JPEG) for photos, PNG for graphics with sharp edges, text or transparency. How each format works, when each wins and what to use on a website today.Updated 4 Oct 2026 - Speed14 min read
What is a CDN? What it fixes for speed, and what it does not
A CDN (content delivery network) is a set of servers around the world that keep copies of your files and answer each visitor from the nearest one. What that speeds up, what it cannot, and how to set one up without caching the wrong pages.Updated 4 Oct 2026 - Speed19 min read
HTTP/2 and HTTP/3 explained: what they change for speed and how to turn them on
HTTP/2 loads every file of a page over one connection at once; HTTP/3 does the same over QUIC with a faster handshake. What each changes, how to check yours and how to turn them on.Updated 28 Sept 2026 - Speed11 min read
AVIF vs WebP vs JPEG: the best image format for the web
AVIF vs WebP: AVIF usually makes photos smaller at the same look, WebP encodes faster and is the safer all-rounder, and JPEG is still fine in a few places. Which format for which image, the quality settings that work, and how to serve a fallback.Updated 27 Sept 2026 - Speed21 min read
Core Web Vitals explained: LCP, INP and CLS, thresholds and how to pass
Core Web Vitals are three Google metrics for how a page feels to real visitors: loading (LCP), responsiveness (INP) and visual stability (CLS). What each measures, the thresholds and how to pass.Updated 27 Sept 2026 - Speed12 min read
Cumulative Layout Shift (CLS): what it is and how to fix it
Cumulative Layout Shift scores how much a page jumps while you use it; good is 0.1 or less. Find the element that moves, then reserve its space with width and height, aspect-ratio or a fixed slot. Covers images, ads, embeds, banners and fonts.Updated 27 Sept 2026 - Speed14 min read
First Contentful Paint and Speed Index: what they measure and what moves them
First Contentful Paint (FCP) is the moment the first text or image appears; Speed Index is how quickly the rest of the screen fills in. What each measures, good values, how they relate to LCP, and the fixes that move them.Updated 27 Sept 2026 - Speed14 min read
font-display: swap, preload and self-hosting: web fonts without layout shift
font-display: swap shows text at once in a fallback font instead of hiding it while the web font downloads. Add it, preload two fonts, self-host and subset them, and tune the fallback so nothing jumps.Updated 27 Sept 2026 - Speed14 min read
How to choose a web host: compare measured speed, not reviews
How to choose a web host: pick a data centre near your visitors, match the plan type to your site, then compare cached and uncached TTFB of your own site on each candidate and the field data of sites already there.Updated 27 Sept 2026
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