Short answer
New to website speed? Start with Core Web Vitals explained, then field data vs lab data. If you are weighing whether to pay for help, read what Google says about speed and SEO and the cost guide.
Understanding the measurements
- Core Web Vitals explained: what LCP, INP and CLS measure, Google's thresholds and why the 75th percentile matters.
- Field data vs lab data: why PageSpeed Insights shows two sets of numbers and which to act on when they disagree.
- Website speed and SEO: Google's exact wording on Core Web Vitals and rankings, and what it does not promise.
Fixing specific problems
- How to improve INP: the three phases of an interaction and the JavaScript changes that make pages respond sooner.
- Image formats and responsive images: AVIF, WebP and SVG, srcset and sizes, and safe lazy loading.
- Caching and CDNs for small websites: Cache-Control directives, cache busting and what must never be cached.
- Third-party scripts and tag bloat: a step-by-step audit of analytics, chat, ads and widgets.
- WordPress plugin bloat: why plugin cost matters more than plugin count, and how to measure it.
- Mobile performance on slow networks: why phones fail more often and how to test realistically.
Planning and budgeting
- Website speed optimization cost: published 2026 price ranges and what each pricing model buys.
How these guides are written
Every guide is written by our editor, Grace Cooper (a pen name), and checked against primary sources such as web.dev, Google Search Central, Chrome for Developers, MDN and the documentation of the platforms we discuss. Secondary and commercial sources are labeled as such in each source list. When Google changes a threshold or a metric, as it did when Interaction to Next Paint replaced First Input Delay in March 2024 [1], the affected guides are updated and the date at the top changes. Our editorial policy explains the process in full.
The guides are meant to be useful whether or not you ever hire us. If you would rather have someone look at your site, the free planner helps you write a brief, and the contact page explains how to request a first review.
Sources
Opened and checked on November 3, 2026.
- Interaction to Next Paint becomes a Core Web Vital on March 12, web.dev blog, Jeremy Wagner and Rick Viscomi. Primary announcement, last updated January 31, 2024.