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Web Vitals | Articles | web.dev
Published: May 4, 2020 Optimizing for quality of user experience is key to the long-term success of any site on the web. Whether you're a business owner, marketer, or developer, Web Vitals can help you quantify the experience of your site and identify opportunities to improve. Overview Web Vitals is an initiative by Google to provide unified guidance for quality signals that are essential to deliv
The Cost of Javascript Frameworks - Web Performance Consulting | TimKadlec.com
There is no faster (pun intended) way to slow down a site than to use a bunch of JavaScript. The thing about JavaScript is you end up paying a performance tax no less than four times: The cost of downloading the file on the network The cost of parsing and compiling the uncompressed file once downloaded The cost of executing the JavaScript The memory cost The combination is very expensive. And we a
A Tour of Inline Caching with Delete
If you search for any JavaScript performance advice, a very popular recommendation is to avoid the delete operator. Today, this seems to be good advice, but why should it be vastly more expensive to delete a property than to add it? The goal of my internship at Apple this winter was to improve the performance of the delete operator in JavaScriptCore. This has given me the opportunity to learn abou
Slow Code HATES him! Optimising a web app from 1 to 60fps
Slow Code HATES him! Optimising a web app from 1 to 60fps This post explores my experience optimising a web app through iterative improvement. The app uses Svelte, but you don’t need any prior experience, and most of what I discuss applies to any web app. It follows on from Embrace your Obsessions! so if you want to learn more about Minesweeper and the context of this post, give it a read. After m
Metrics, Logs, and Traces in JavaScript Tools
Home Ideas Writing & Speaking Book Tactics, Strategy, Principles About Bio, Talks, Photos Subscribe RSS, Newsletter, Mixtape I was listening to the Official AWS Podcast’s episode on Observability and was struck by how much thought has been given towards improving tools for investigating when things go wrong. I realized that we could probably have something to learn by applying this lens to the Jav
Performance Tips for Background Video
Doug Sillars (@dougsillars) is a leading mobile developer advocate and evangelist. He is widely known as an expert in mobile application architecture, especially when it comes to performance. Doug has worked with thousands of developers around the world, helping them improve the speed, battery life and customer satisfaction of their applications (both native and web). The author of O'Reilly's "Hig
Faster apps with JSON.parse (Chrome Dev Summit 2019)
Because the JSON grammar is much simpler than JavaScript’s grammar, JSON can be parsed more efficiently than JavaScript. This knowledge can be applied to improve start-up performance for web apps that ship large JSON-like configuration object literals (such as inline Redux stores). Presented by: Mathias Bynens - https://goo.gle/2Oh2tq6 More info → https://goo.gle/33czWGH #ChromeDevSummit All S
Fixing layout instability | Articles | web.dev
[ { "name": "", "entryType": "layout-shift", "startTime": 210.78500000294298, "duration": 0, "value": 0.0001045969445437389, "hadRecentInput": false, "lastInputTime": 0 } ] In this example there was a single very tiny shift of 0.01% at 210ms. Knowing the time and severity of the shift is useful to help narrow down what could have caused the shift. Let's turn back to WebPageTest for a lab environme
Techniques to make a web app load fast, even on a feature phone | Articles | web.dev
At Google I/O 2019 Mariko, Jake, and I shipped PROXX, a modern Minesweeper-clone for the web. Something that sets PROXX apart is the focus on accessibility (you can play it with a screenreader!) and the ability to run as well on a feature phone as on a high-end desktop device. Feature phones are constrained in multiple ways: Weak CPUs Weak or non-existent GPUs Small screens without touch input Ver
✩ Wikipedia's JavaScript initialisation on a budget
This week saw the conclusion of a project that I've been shepherding on and off since September of last year. The goal was for the initialisation of our asynchronous JavaScript pipeline (at the time, 36 kilobytes in size) to fit within a budget of 28 KB – the size of two 14 KB bursts of Internet packets. In total, the year-long effort is saving 4.3 Terabytes a day of data bandwidth for our users'
Is postMessage slow? — surma.dev
Toggle dark mode No, not really. (It depends.) What does “slow” mean? I said it before, and I will say it again: If you didn’t measure it, it is not slow, and even if you measure it, the numbers are meaningless without context. That being said, the fact that people will not even consider adopting Web Workers because of their concerns about the performance of postMessage(), means that this is worth
The cost of JavaScript in 2019 · V8
Show navigation Note: If you prefer watching a presentation over reading articles, then enjoy the video below! If not, skip the video and read on. “The cost of JavaScript” as presented by Addy Osmani at #PerfMatters Conference 2019.One large change to the cost of JavaScript over the last few years has been an improvement in how fast browsers can parse and compile script. In 2019, the dominant cost
高速化の観点から new Array(100) を使わない方が良い理由
別件で V8 の JIT コードの逆アセンブルを眺めている時に気づいたのですが、JavaScriptで new Array(100) という形で配列を作るのは、高速化の観点から言うと V8 においては避けるべき書き方です。 高速化を求める方は、 new Array() や [] で作成して Array#push で追加していくのが良いでしょう。この記事では、その理由を説明します。 今回の記事は、以下の V8 のブログ記事を参考にしております。 https://v8.dev/blog/elements-kinds 「詰まった配列(Packed Array)」と「穴あき配列(Holey Array)」 v8 は内部的に、その配列がどういうタイプの配列であるかの状態を記録しており、その情報を利用して最適化を適用します。状態は内部的には21個あるのですが、今回話題にするのは、その中でも「詰まってい
Improving third-party web performance at The Telegraph
At The Telegraph we’re currently going through a process of rebuilding our public-facing website. This gives us the opportunity to take learnings from the existing build but also write some of the code from scratch. You can see our progress so far on pages such as Gaming and Culture. We can monitor the impact this has on metrics across usability, performance and accessibility. We’re incredibly pas
Faster input events with Facebook’s first browser API contribution
Faster input events with Facebook’s first browser API contribution UPDATE Nov. 19, 2020: As of Chrome 87, the IsInputPending API is now available without the origin trial. The latest API incorporates a number of updates we’ve made in response to feedback from the origin trial, as well as from other members of the W3C Web Performance working group. The time it takes for an interaction to go from th
アメブロ2019: こえのブログでのPWA | CyberAgent Developers Blog
こえのブログは「声で書くブログ、声で聴くブログ、声で観るブログ」をコンセプトに書き手、読み手双方にバージョンアップしたブログを提供するアメブロの新機能です。 投稿者は端末に向かって喋るだけで、その音声が活字化されブログとして公開できます。閲覧者は活字化された文字を通常のブログと同じように読めるほか、音声を聴きながらでもコンテンツ消費できます。 モバイル端末、テレビ端末やスマートスピーカーなどの普及により、今後ますます増えると予想される利用形態に対して、それぞれに適した形でコンテンツを提供できるように挑戦しています。 この記事では、技術的な側面を中心にこえのブログを紹介します。 こえのブログは、文字でも音声でもコンテンツ消費できるのが特徴です。読者の方へのメッセージや質問に回答など利用法は様々です。龍玄としさんやクロちゃんさんなど著名人の方の声も聴けます。 できる限りサーバーにアクセスしない
setTimeout()/setInterval() are now deferred during page load (Affecting) | Firefox Site Compatibility
Starting with Firefox 66, timers added with the window.setTimeout or window.setInterval method during page load will be given a low priority and deferred until an idle time is available or the loading is complete. While this change aims at improving the performance of complex web applications like Google Docs, unexpected race conditions could occur if the initialization code is not designed proper
Vueで作ったSPAの表示速度改善でやったこと - Qiita
Vue.jsを全く触ったことないところから始めて、SPAのWebサービスを2ヶ月でリリースできたのだけど、同僚から「ちょっと表示が遅いですね」と言われた。それまではとにかく機能を動かすのとソースコードの見通しを悪くしないようにというのだけ気にしてて、パフォーマンスをあまり気にしていなかった。 で、少し気になって試しにGoogleのPageSpeed Insightsで計測してみたところ、なんとモバイルで26点だった。PCの方でも52点。 これはマズイと思い、いろいろ試行錯誤してモバイル72点、PCは98点まで改善したので、以下したことをまとめておく。 Google Fontsの読み込みの最適化 まずはこれ。Google Fontsはカッコイイけど、公式にあるCSSでの読み込みをするとめちゃくちゃ表示を遅くしてしまう。 AMP にも対応！Google Fonts を preload で先読み
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[V8] Array.prototype.splice ~100x slower in V3 with symbol polyfill · Issue #677 · zloirock/core-js