Website speed guides

Step-by-step fixes for every part of the loading timeline our 8-region test measures — DNS and connections, server response, page weight and caching. Written by the engineers who run the tool.

Request timeline with DNS, TCP and TLS segments followed by a long server-wait bar that shrinks to a short one after HTML is cached at a CDN edge

Server & TTFB

How to reduce TTFB (time to first byte): causes, targets and fixes that work

Reduce TTFB by caching HTML at the edge, fixing slow database queries, removing redirects and moving content closer to users. Targets, causes and configs.

9 min read · Updated Oct 4, 2026

CDN & Edge

What a CDN is and how it makes your website fast worldwide

A CDN serves files and cached HTML from edge servers near each visitor. Learn cache hits, keys, TTLs, purging and headers, and how a CDN cuts far-region TTFB.

9 min read · Updated Oct 4, 2026

A large camera photo being compressed into smaller AVIF and WebP files at several widths, with arrows pointing to a phone, a laptop and a desktop screen

Images & Media

Image optimization for web performance: AVIF, WebP, responsive images and lazy loading

Image optimization guide: pick AVIF or WebP, set quality, serve responsive images with srcset, prevent CLS, lazy-load correctly and prioritize the LCP image.

9 min read · Updated Oct 4, 2026

A browser window pulling CSS, JavaScript, font and image files from a local cache drawer instead of a distant server, with a stopwatch showing a faster second visit

Caching

Cache-Control and browser caching: how to make repeat visits instant

Browser caching: set Cache-Control headers by file type, use immutable and stale-while-revalidate, bust caches with content hashes and speed up repeat visits.

9 min read · Updated Oct 4, 2026

Three gauge dials labeled LCP, INP and CLS with their needles in the green zone, above a browser window and a world map

Core Web Vitals

Core Web Vitals explained: how to improve LCP, INP and CLS

Core Web Vitals explained: what LCP, INP and CLS measure, the good thresholds at the 75th percentile, and the practical fixes that move each metric to green.

9 min read · Updated Oct 4, 2026

World map with fiber-optic routes linking Seoul, Tokyo, Singapore, Sydney, Virginia, Oregon, Frankfurt and London, each route labeled with its round-trip time

Global Performance

Why your website is slow in other countries: latency, distance and fixes

Your website is slow in other countries because every round trip to a distant server adds latency, and a page load needs many. Learn the physics and the fixes.

9 min read · Updated Oct 4, 2026

Browser loading timeline in which stylesheet and script bars hold back the first paint until they are deferred

Front-end

How to eliminate render-blocking CSS and JavaScript

Render-blocking CSS and JavaScript delay first paint. Learn defer vs async, critical CSS, preload, font-display and third-party fixes, with copy-paste HTML.

9 min read · Updated Oct 4, 2026

Timeline comparing the round trips TCP with TLS 1.2, TCP with TLS 1.3 and QUIC need before the first byte arrives

Network & Protocols

HTTP/2, HTTP/3 (QUIC) and TLS 1.3: protocol-level speedups explained

HTTP/3 over QUIC and TLS 1.3 cut connection setup from three or four round trips to one or two. Learn how they work, how to enable them and how to verify.

9 min read · Updated Oct 4, 2026

Measure before and after

Run a free test from 8 regions, apply a fix, and test again to see the difference in each region.

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