We built Monitoring Speed PLUS on years of hands-on experience optimizing performance for dozens of clients.
LCP Element
For optimizing LCP, it’s essential to be able to find the “LCP element,” which is the largest element in the browser’s viewport for a given user. The display time of this element determines the LCP metric.
LCP Optimization
Let’s explore what problems with the Largest Contentful Paint (LCP) metric you may encounter and how to optimize the metric as efficiently as possible.
LCP: Lazy-loading Images
Lazy loading is a foundational and highly effective way to speed up page loads. We recommend conservatively deferring all images outside the first viewport. Be careful applying lazy loading to images that are LCP elements, as it can actually hurt speed.
BFcache
Back/forward cache (BFcache) is a browser optimization that makes back and forward navigation instant. It greatly improves browsing experience, especially for users on slower networks or devices.
Cloudflare
Cloudflare acts as a gateway between your website and its visitors. Unlike a standard CDN (Content Delivery Network), it’s more than just a system for distributing images and files.
CLS: How to Keep Height?
This article explains why and how to ensure element dimensions at the HTML or CSS level for elements inserted asynchronously, such as <img>, <iframe>, or JavaScript components.
Cookie Banners and Website Speed
Is your site speed dialed in? Great, but you may not have deployed a cookie banner yet.
Chrome UX Report (CrUX)
Chrome UX Report (CrUX) is a public data set provided by Google that collects and anonymously analyzes data about real user experience when browsing the web with the Chrome browser.
DOM Optimization: The Foundation of Speed and SEO
A large and inefficient page structure (Document Object Model, i.e., the DOM) can significantly slow your web and negatively affect Core Web Vitals metrics. Keeping it reasonably small and as efficient as possible is essential for the overall technical performance of your project and will impact interaction response speed (INP).
Webfont Optimization
The world of web fonts is like a beauty salon — we all want the best, but we’re not always willing to wait for the stylist to finish. And your visitors? They’re especially impatient.
Gzip and Brotli Compression
In PageSpeed.cz we tackle very specific issues, and we’re often surprised by how deep we go. Data compression was no exception, and we’ll dive into it in this article.
HTML head and speed
We love WebExpo and performance. And we’re big fans of Harry Roberts, whose talks and articles always go in-depth.
React Optimization
React is a popular tool for building modern websites, but speed and interactivity aren’t always automatic. In this article we’ll cover key techniques for optimizing Core Web Vitals—from hydration to DOM work—and show you how to apply them to accelerate your React projects.
INP and setTimeout()
Using setTimeout() to optimize long JavaScript tasks that block user interactions and degrade metrics such as Total Blocking Time (TBT) or Interaction to Next Paint (INP), a key part of Core Web Vitals.
Why Monitor?
Measuring speed once in a while isn’t enough. Without continuous speed monitoring you won’t uncover hidden issues, you’ll lack a data history for analysis, and you’ll easily miss trends that could cost your business conversions and visitors.
Backend Optimization
The backend plays a pivotal role in site speed optimization, because proper code- and server-side optimization can eliminate delays that often arise when processing requests and delivering content.
CLS Optimization
Let’s take a look at how to avoid CLS problems and how to remove them when they occur.
INP Optimization
INP isn’t the easiest metric to optimize, so we’ve drawn from our experience the most common problems and how to fix them.
Image Optimization
Even everyday site owners can tame their images and make them work for you. Use WebP or AVIF, compress well, and don’t forget lazy loading.
Shoptet Optimization
Shoptet is fast if you don’t slow it down. We show how to optimize speed: what harms, what helps, and how to monitor your store.
Vue.js/Nuxt.js Optimization
Boost Vue.js site speed with SSR, lazy loading, and more. Faster performance means happier users and higher conversions.
WordPress Speed Optimization
Site speed isn’t just a cosmetic detail—it’s a key factor shaping the success of your online business. Slow WordPress sites are often caused by poor plugin choices, bloated themes, or a lack of optimization know‑how.
Performance budgets
Performance budgets is a methodology for keeping web page speed at the level we set. Think of a “budget” as a limit on values for different metrics.
Why Website Speed?
Psychology, conversions, and Google — why you should have a fast website too.
Speculation Rules
The Speculation Rules API lets us preload or even prerender another page. This approach enables near-instant loading of the page a user navigates to, improving their overall web experience.
Study: Chats and Speed
Live chat is used by 20% of Czech e-commerce operators. But how do these widgets affect site speed?
Study: One CSS File or Many?
In the PageSpeed.cz team we have several evergreen discussions, and one of the perennial questions is: Is it faster to have many small CSS files split by components, or a single large file?
Synth vs. CrUX vs. RUM
In this article, we clarify the differences between the various types of web speed measurement. We’ll discuss synthetic data (“synth”), data from Google users (“CrUX”), and data from all users (“RUM”).
Navigation Types
Understanding the different navigation types is important because some are much faster than others. From a speed optimization perspective, the goal is to convert as many users as possible to fast navigation types.
Web Vitals in the Browser
Core Web Vitals are the metrics we use to evaluate website performance in areas such as loading speed, interactivity, and layout stability. These metrics are increasingly important for delivering a good user experience, and Google uses them as a ranking factor in search results.
WebP Images
Page load speed is often measured in seconds. The WebP image format can be the secret weapon to trim kilobytes and push performance toward perfection.