Newsletter Archive

May 2025

How to Speed Up Your Shoptet E-Shop? Our Tips and Tricks

How to Speed Up Your Shoptet E-Shop? Our Tips and Tricks

Having a Shoptet e-shop provides a solid foundation, but even the best shops require regular maintenance. In our article, you'll discover common issues on this platform, such as clumsy design tweaks and adding third-party plugins and scripts without monitoring their impact on speed.

Next.js Performance Optimization

Next.js Performance Optimization

Let’s dive into the minds of developers optimizing LCP for a Next.js project. This article covers key topics like deferring non-critical resources in the header, fixing hydration issues, and addressing double rendering of LCP elements.

Virtual Meetups: PerformanceObserver

Virtual Meetups: PerformanceObserver

Do you live and breathe making websites faster every day? Then the virtual meetups of PerformanceObserver are for you. The web speed community is scattered worldwide, and this is a chance to connect. So far, they have mainly shared talks on INP.

April 2025

How to Optimize Web Fonts

How to Optimize Web Fonts

TTF and SVG fonts haven't completely disappeared. To avoid speed 'faux pas' on your website, read our article on web font optimization. Discover the necessary formats today and how to eliminate unnecessary characters in font styles.

The best optimizations for React and Next.js

The best optimizations for React and Next.js

Dive into real case studies revealing challenges, solutions, and results. Look forward to advanced optimization techniques in production applications running on React/Next.js for major projects like DoorDash, Vio, and Preply.

From zero to one hundred: How QuintoAndar optimized INP

From zero to one hundred: How QuintoAndar optimized INP

QuintoAndar, Brazil's largest rental portal, improved its INP from 1000 ms to 216 ms. This was achieved through async optimizations, React transitions, and removing unnecessary scripts. Consequently, web conversions increased by 36% year-over-year.

March 2025

Technical SEO and website speed matter

Technical SEO and website speed matter

Loading speed and SEO make the difference between a selling website and one that fades into mediocrity. Investing in these areas can provide a competitive edge that's hard to catch up to. Find more arguments in Martin Stepánek's article.

February 2025

Size Matters: Effective DOM Management

Size Matters: Effective DOM Management

An inefficient page structure can significantly slow down your website and negatively impact your Core Web Vitals. Michal Matuška shares his extensive experience, explaining why DOM structure is crucial, how to measure it, and how to optimize the DOM to speed up your site.

Many ways to break down long tasks in JavaScript

Many ways to break down long tasks in JavaScript

Long synchronous tasks in JavaScript affect all websites. Alex MacArthur wrote a great article discussing task splitting options, mentioning async/await, setTimeout, scheduler.postTask, and requestIdleCallback. Speed enthusiasts will appreciate it.

Everything you need to know about performance budgets

Everything you need to know about performance budgets

Zuzana Šumlanská discusses performance budgets in her latest article. Want to set measurement limits correctly? Analyze the data, set limits based on worst-case scenarios, start with key metrics, and regularly review your measurements. For more tips, read the article.

January 2025

Size Matters: Effective DOM Management

Size Matters: Effective DOM Management

An inefficient page structure can significantly slow down your website and negatively impact your Core Web Vitals. Michal Matuška shares his extensive experience, explaining why DOM structure is crucial, how to measure it, and how to optimize the DOM to speed up your site.

Many ways to break down long tasks in JavaScript

Many ways to break down long tasks in JavaScript

Long synchronous tasks in JavaScript affect all websites. Alex MacArthur wrote a great article discussing task splitting options, mentioning async/await, setTimeout, scheduler.postTask, and requestIdleCallback. Speed enthusiasts will appreciate it.

Everything you need to know about performance budgets

Everything you need to know about performance budgets

Zuzana Šumlanská discusses performance budgets in her latest article. Want to set measurement limits correctly? Analyze the data, set limits based on worst-case scenarios, start with key metrics, and regularly review your measurements. For more tips, read the article.

January 2025

The big web speed forecast: what will 2025 bring?

The big web speed forecast: what will 2025 bring?

The start of the year invites trend predictions. According to Uxify, 2025 will focus on the INP metric, AI integration in optimizations, moving away from SPA architecture, and supporting Core Web Vitals in all modern browsers. We look forward to what 2025 will bring.

Updates in DevTools and the use of AI for performance

Updates in DevTools and the use of AI for performance

Chrome DevTools now offers an experimental AI assistance feature to help with website speed. After recording the timeline, you can ask the AI to analyze specific issues, just like in other tools. Have you tried this functionality yet?

Socials Podcast: How Does Website Speed Impact Business?

Socials Podcast: How Does Website Speed Impact Business?

Martin Michálek will answer that, having spoken with Otakar Lucák and Daniel Bauer. This time, they focused on the impact on marketing and business websites, discussing business metrics and specific advice on improving speed.

December 2024

Keyword Vitals: Monitor speed directly in the SERP

Keyword Vitals: Monitor speed directly in the SERP

A valuable tool for assessing the impact of speed on SEO is the Chrome extension called Keyword Vitals. After installation, simply search for a keyword on Google, and you'll see Core Web Vitals metrics along with their correlation to rankings and target values.

How to use Speculation Rules?

How to use Speculation Rules?

The Speculation Rules API is still new, and we welcome an article from Harry Roberts. It explains how to use prefetch for preloading and reducing TTFB. We appreciate Harry's deep insights and layered approach to Speculation Rules. Very valuable!

Performance.now(); Beyond Core Web Vitals

Performance.now(); Beyond Core Web Vitals

After two years, Michal Matuška attended the Performance.now() conference in Amsterdam, featuring industry leaders like Harry Roberts, Tammy Everts, and Paul Calvano. Want to discover the hot topics in speed? Read our article.

November 2024

React Optimization: 6 Tips for Better Core Web Vitals

React Optimization: 6 Tips for Better Core Web Vitals

While React offers smart optimization techniques, its performance ultimately depends on how developers use it. In Michal Matuška's article, you’ll learn how to leverage Suspense, Server Components, and the impact of DOM size on speed.

Speed optimization: How to assist on the backend

Speed Optimization: How to Help on the Backend

Think you can’t help with website speed on the backend? Think again. There are many ways to influence speed. Zuzana Šumlanská compiled tips for Help, including lossless compression, UTM parameters, Early Hints, and Speculation Rules API.

Why do we all want Safari to support Core Web Vitals?

Why do we all want Safari to support Core Web Vitals?

Google's Core Web Vitals metrics have become an industry standard, but we can only measure them in Chromium-based browsers. We don't know the metric values in Safari. Read Brian Luis Ramirez's article to understand why this should change.

October 2024

Why is this website so fast?

Why is that website so fast?

Do you ever have the same question? Check out Wes Bose's video where he discusses the technologies behind McMaster.com. He covers specific techniques like using preload and the Speculation Rules API. Want a teaser? The website in the video uses jQuery.

September 2024

The World of Lighting: How to avoid speed issues in redesign?

The World of Lighting: How to Avoid Speed Issues in Redesign?

Redesigning a website, especially when the current version is already lightning-fast, is no easy task. However, we succeeded with our client, the SvetSvitidel.cz e-shop. We documented our experiences and recommendations in a case study on how to tackle such a project.

New page speed measurement in Chrome DevTools

New page speed measurement in Chrome DevTools

In Chrome version 129, developers can look forward to new features in the Performance tab. It provides a different perspective on locally measured speed metrics and compares results with metrics obtained from real users. This could replace the well-known Web Vitals extension.

Speed Brain: New Speed Feature from Cloudflare

Speed Brain: New Speed Feature from Cloudflare

Cloudflare introduces a new service that preloads pages using the Speculation Rules API, potentially reducing overall load time. Speed Brain currently preloads static content, with plans to implement prerendering in the future.

August 2024

How to Find the LCP Element?

How to Find the LCP Element?

We’ve written a guide on reliably finding the LCP element. The Largest Contentful Paint metric is crucial, but it can be tricky to identify. Our guide shows you how to find the LCP element in PageSpeed Insights, Lighthouse, or DevTools.

Červenec 2024

PageSpeed.cz Monitoring Version 4.4

PageSpeed.cz Monitoring version 4.4

Our latest tool version is even better. We’ve put a lot of effort into improving the help section and automating PLUS monitoring. The main update will delight anyone who loves instant-loading pages.

Navigation Types: A fresh perspective on user experience

Navigation Types: A fresh perspective on user experience

Fast loading is great, but what about instant loading? Understanding different types of navigation is crucial, as some are much faster than others. The goal is to transition as many users as possible to faster navigation types. We’ve detailed this update in our documentation.

June 2024

Clarify the differences: Synthetic, CrUX, and RUM

Clarify the differences between synthetic, CrUX, and RUM

From experience, we know that differences in speed measurements can confuse even knowledgeable individuals. Let’s define what synthetic data (“synth”), Google user data (“CrUX”), and all user data (“RUM”) mean.

What's New in Performance for Chrome Dev Tools

What's New in Performance in Chrome DevTools?

DevTools now features new functionalities. For instance, in the Network panel, you can better debug Early Hints headers, and in the Performance tab, there’s a new checkbox for “Enable CSS selector stats,” allowing you to analyze selector performance.

Recordings from WebPerf.cz meetups are available online

Recordings from WebPerf.cz meetups are available online

This year, we organized two meetups for the WebPerf.cz community, one in Prague and one in Bratislava. Both events were successful, and now you can access the insights from them in one place, including our concise notes.

May 2024

Speed Monitoring Version 4.3

Speed Monitoring in Version 4.3

We continuously improve our tool, pagespeed.cz. We've added a speed development graph showing the 75th percentile and included results from the Monitor in the Summary. Our new documentation will also share our insights with you.

Tips for optimizing the LCP metric

Tips for optimizing the LCP metric

The latest addition to our documentation is an article on optimizing LCP metrics. Learn how to use Priority Hints, preloading, and lazy loading to enhance your website's speed. Are you already using the efficient WebP image format everywhere?

Chrome extensions and their impact on speed

Chrome Extensions and Their Impact on Speed

DebugBear released a new study on the impact of extensions on browser performance. The results are intriguing. The influence of extensions is significantly higher than three years ago. Who are the main culprits for performance slowdowns now? AI and Copilot extensions like Monica, Merlin, and Sider.

April 2024

INP Uncovered: Enhance User Experience and Boost Conversions

INP Uncovered: How to Enhance User Experience and Boost Conversions

Martin Michálek wrote a comprehensive article for Lupa.cz about the INP metric, providing all the essential information in an accessible, non-technical format. The key takeaway? Address INP as soon as possible: start monitoring, provide instant feedback to users, and shorten lengthy tasks.

Launching a new documentation zone

Launching a new documentation zone

We’ve long needed a single place to gather all speed-related information, so we’re launching PageSpeed.cz. Here, you’ll find extensive knowledge on web speed, metrics, and eventually documentation for the tool. We’ll continuously update this resource, as we have big plans for it.

March 2024

BFcache: Speed Up Users' Browsing History Navigation

BFcache: Speed Up Users' Navigation in Browsing History

Back/forward cache (BFcache) is a browser optimization that enables instant navigation back and forth. It significantly enhances the browsing experience, especially for users on slower networks or devices. To implement it on your site, check out Radek's article on the blog.

Step-by-step: How to optimize INP

Step by step: How to optimize INP

There’s never enough good content on INP, and this article by Andy Davies is excellent. It covers identifying long interactions and provides a step-by-step guide on how to interpret and optimize them.

Improvements to the Speculation Rules API

Improvements to the Speculation Rules API

Starting with Chrome version 122, the Speculation Rules API enhancement is available. This native feature pre-renders links you can click from the current page, ensuring instant loading. A new option allows you to set eagerness, specifying when to trigger the rules.

February 2024

PageSpeed.cz tester version 4.2 is out

PageSpeed.cz tester version 4.2 is out

We have recently launched a new version of the tester with updates based on user requests from the PLUS plan. You can now test more URLs or domains for an additional fee, we’ve added a metric for monitoring third-party JS, included INP, and you can now send notifications to multiple Slack or Teams channels. We've made many changes, so be sure to read our article.

How to Embed 3D Models on the Web

How to embed 3D models on your website

3D models are still a niche topic, so we appreciate Jason Grigsby's article covering the most common components for displaying 3D models, file formats, user experience, optimizations, and the potential future hinted at by Apple with the new HTML element <model>.

Performance Inequality Gap 2024

Performance Inequality Gap 2024

Curious about the performance comparison between the latest iPhones and a budget Android device? Which countries can dream of 5G mobile connectivity? And what does all this mean for developers in terms of website speed? Alex Russell's article answers these questions.

January 2024

Paid PLUS plan: Speed monitor and notifications

PLUS Plan: Speed Monitor and Notifications

The Speed Monitor is a core feature of our PLUS plan. We focused on simplicity, automation, and notification accessibility across various channels during its development. How did we do? Judge for yourself in the detailed article about the Monitor.

Practical optimization of the CLS metric

Optimizing CLS Metrics in Practice

Is an unmet CLS metric bothering you? Radek Šír has outlined common CLS issues based on our extensive experience and how to resolve them. Did you know you need to perform an action in the interface within 500 ms after user interaction?

Guide to measuring INP with Puppeteer

Guide to measuring INP with Puppeteer

INP will soon replace FID in Core Web Vitals. Many developers are grappling with INP, facing challenges in accurate measurement and problem detection. Tsvetan Stoychev shares his attempt to automate INP measurement using Puppeteer.

December 2023

Estimate your return on investment in speed

Estimate Your ROI on Speed

A fundamental question for website owners is whether their investment in speed will pay off. With an ROI calculator, you can estimate your return. Just know values like monthly traffic, conversion rate, and order value.

November 2023

Article: Paid PLUS Plan

Article: Paid PLUS Plan

Learn more about the PLUS plan in our article. It’s designed for anyone who professionally manages websites and understands that speed matters, as it improves business metrics. If you’re a website owner, developer, or marketer, read on.

Understand speed in Google’s new course

Understand speed in a new course from Google

Google has released a new course on web speed at web.dev, aimed at beginners. It covers key concepts and approaches to speed, offering techniques for improvement. Trust us, it's excellent.

October 2023

Launching Speed Test version 4.0

Launching Speed Test version 4.0

We are excited to launch our new tester after months of development. Look forward to many updates, including new metrics, reports, and graphs.

A closer look at the INP metric

A closer look at the INP metric

The Interaction to Next Paint metric is stricter than the outdated FID. Optimizing this metric can take several months, so now is the best time to address it.

September 2023

Report from SmashingConf Freiburg 2023

Report from SmashingConf Freiburg 2023

Radek Šír attended the renowned Smashing Magazine conference to gather insights on speed optimization for you. Andy Davies from SpeedCurve fine-tuned the INP metric on-site, and thanks to Radek, you'll learn about the highlights.

How to Boost Ad Revenue by 9% Using BFcache

How to Boost Ad Revenue by 9% Using BFcache

A great case study from Yahoo! JAPAN News on speed optimization using BFcache (Back/Forward Cache), which we are also experimenting with for our clients. Besides increased ad revenue, the test showed a 2.26% rise in mobile page views.

August 2023

Our Guide to the CLS Metric

Our Guide to the CLS Metric

The Cumulative Layout Shift metric has long been part of Core Web Vitals. It measures unwanted layout shifts, and Radek Šír can optimize it. Read his article to learn how to improve your CLS scores.

Video: The Cost of JavaScript (2023)

Video: The Cost of JavaScript (2023)

This is a fascinating and regularly updated talk on JavaScript's impact on speed. The author? Addy Osmani, of course. We recommend developers watch how JS increasingly negatively affects website performance and what can be done about it.

INP a SEO lidé

INP and SEO Professionals

With the new INP metric, we won't let you rest. Because we can't. In the article “Interaction to Next Paint: What SEOs Need to Know,“ Wix experts view the interactivity metric through the lens of SEO. How does it differ from FID? How can you optimize it?

July 2023

Can we replace the GIF format with something faster?

Can we replace the GIF format with something faster?

The GIF format is a key part of web technology, but it's been around for 36 years. Is there a more modern and efficient format for animated images? The short answer is yes. Read the article below for a comparison of WebM, AVIF, MP4, and WebP.

June 2023

10 New Technologies and Tools for Developers

10 new technologies and tools for developers

Martin Michálek compiled ten tips on the latest web speed updates. Look forward to practical code examples and insights on size-adjust, priority hints, BF cache, and the still underused image formats WebP/AVIF.

Capo: Correct Order of Elements in <head>

Capo: Correct Order of Elements in <head>

Harry Roberts addressed the order of elements in the <head> a few months ago, and it was a significant topic. Now, a Chrome extension by Rick highlights the current state on the page.

How Fast Do Selected European News Websites Load?

How quickly do selected European news websites load?

SpeedCurve has prepared a comprehensive comparison of loading speeds for various websites. You can view sites by focus, location, and specific metrics. How did European news websites, including Novinky.cz, perform in the LCP metric?

May 2023

Interaction to Next Paint Will Be Part of Core Web Vitals

Interaction to Next Paint will be part of Core Web Vitals

Google announced a major change in Core Web Vitals. The First Input Delay metric will be replaced by Interaction to Next Paint (INP) in March 2024. This new metric will better reflect the impact of JavaScript on browsing an already loaded page.

April 2024

How to Test Web Vitals Metrics in Your Browser?

How to test Web Vitals metrics in your browser?

Developers still lack knowledge about testing Core Web Vitals in the browser, which is as crucial as implementing features well. Zuzana Šumlanská discusses in our blog why you should avoid using Lighthouse for testing and focus on Dev Tools instead.

Change in LCP element evaluation

Change in LCP element evaluation

Since around April 6, 2023, Google changed the rules for evaluating LCP elements, significantly limiting the ability to use various hacks for this metric. Images with less than 0.05 bits of image data per pixel are not considered LCP elements. This typically applies to large, simple images that cover the entire viewport or placeholder images.

WebExpo 2023: Our perspective on performance

WebExpo 2023: Our perspective on performance

WebExpo was beautiful and intense. Martin Michálek shares his impressions from this year's conference, focusing on speed. He discusses intriguing talks by Harry Roberts and Scott Jehl, along with insights from his own presentation on Cumulative Layout Shift.

March 2023

PageSpeed.cz Speed Tester: New features in version 3.1

PageSpeed.cz Speed Tester: What's New in Version 3.1

We are continuously improving our tester. Version 3.1 introduces customizable test settings, new domain types, and enhanced email reports. We've also added the option to download results in JSON format for Lighthouse and removed outdated metrics.

How to Measure Core Web Vitals on SPAs

How to Measure Core Web Vitals on SPAs

Single-page applications can greatly enhance user experience. However, they pose challenges in measuring Core Web Vitals, as 'soft' navigation isn't counted as unique page visits. The new Chrome 110 introduces experimental features to better measure CWV on SPAs.

February 2023

Is your website's compression set up correctly?

Is your website's compression set up correctly?

Brotli and GZIP are the most common types of compression for CSS, JS, and other files. Did you know you can also set the compression level? Higher levels save more data but require more computational power and time. We’ve detailed how to choose the most effective compression level in our article.

Lighthouse 10 will change how the LPS metric is calculated

Lighthouse 10 will change how the LPS metric is calculated

Google is releasing a new version of the Lighthouse tool, which will be reflected in Chrome 112. The TTI metric is being removed from the LPS calculation, while the CLS metric will increase its share to 25%. This and much more will soon be in your browsers.

How to Use Priority Hints, Preload, and Optimize LCP?

How to Use Priority Hints, Preload, and Optimize LCP?

Currently, we have two options for prioritizing files on the web: using preload or priority hints. While they may seem similar, it's important to understand their differences, as explained in Kevin Farrugia's article.

January 2023

What We Achieved in 2022?

What did we achieve in 2022?

Last year was a strong start for PageSpeed.cz. We provided more consulting services focused on web speed optimization and developed our own speed tester. Read about our other successes on our blog.

How to Optimize Website Speed in 2023

How to Optimize Website Speed in 2023

The Chrome DevRel team has compiled a list of recommendations they believe will be most effective for speed optimizations in 2023. Learn about fetchpriority, bfcache, and other ways to speed up your website.

December 2022

Website speed: 12 updates from 2022

Website Speed: 12 Updates for 2022

In this article, we’ll explore some features, techniques, and tools that caught our attention in 2022. Look forward to Early Hints, a change in the calculation of the CLS metric, the CSS property size-adjust, and more.

November 2022

Performance.now() Conference 2022

Performance.now() Conference 2022

At the end of October, we attended the Perf.now() conference in Amsterdam. We heard 14 talks, with the best from Harry Roberts, Ivan Akulov, and Nolan Lawson. Check our article for the full list and details.

Performance Insights: A simpler, clearer view of speed

Performance Insights: A simpler, clearer view of speed

If you want to optimize speed but find the Performance tab in Chrome DevTools complex, try Performance Insights. It displays only the most relevant information, especially regarding Web Vitals. A detailed guide on using the tool is available on the Chrome Developers website.

The Web Performance Calendar is coming soon

The Web Performance Calendar is coming soon

Since 2009, December has been the month for the Web Performance Calendar. This year is no exception—starting December 1st, enjoy daily insights on speed. We believe you'll find it valuable.

October 2022

Element Timing: One Metric to Rule Them All?

Element Timing: Does One Metric Rule Them All?

Is LCP not enough for you? Measure the rendering of a specific element using the Element Timing API, which allows you to mark the element of interest in Chromium-based browsers. When should you use it, and what are its limitations?