Workshop: React Performance 3.0

You will learn how to reproduce, diagnose, and resolve runtime React performance issues to give your app a speed boost.
Mentor: Ivan Akulov, a Google Developer Expert, full-stack software engineer, and performance consultant.
Workshop: React Performance 3.0
Workshop: React Performance 3.0

Workshop description:

There’s a lot of tools and talks about loading performance – but what if every time you click a button in your app, the get slow? Let’s learn how to deal with that.

In this workshop with Ivan Akulov, a Google Developer Expert and a senior performance engineer at Framer, you will learn how to reproduce, diagnose, and resolve runtime React performance issues to give your app a speed boost.

“I’ve had plenty of trainings in the past that were full-frontal “death by powerpoint” where I had wished to do something practical for a change, but not in your workshop” – Patrick

“The format of the workshop is great. We get to actually hear the thought process behind the debugging and profiling, why we chose one technique or the other. We get to reflect on the choices and discuss them live.” – Vyacheslav

“I really liked just watching over Ivan’s shoulder while he did the analysis. Ivan kept things really simple – no sophisticated, expensive tooling, just patiently analyzing the profiles we were taking, seeing why components re-rendered, and showing how to fix them. That was absolutely enlightening!” – Elisabeth



📈 Chrome and React DevTools
How to profile React apps with the Performance pane in Chrome DevTools, the React DevTools Profiler, and third-party tools like why-did-you-render.

🧑🏼‍🎨 Unnecessary Rerenders
How to ensure you’re not re-rendering the whole app every time anything changes (and how to refactor the code when you are).

🏃🏼‍♂️ Browser’s Render Loop
You click a button, and the browser updates the page. What happens between these two bits, and what can make it slow?

🌴 Huge Component Trees
How to reduce the cost of rerenders through memoization and virtualization.

🪙 Expensive Functions
How to optimize expensive render() or event listeners.

🗑️ Layout Thrashing
Why, sometimes, a browser decides to recalculate the whole page’s layout in the middle of a function – and how we can avoid it.

⛓️ Chains of Rerenders
A single piece of code may sometimes triggers multiple renders in a row. Let’s learn to notice, diagnose, and fix these cases.

🧊 Bundle Size and Hydration
Large bundles and slow hydration are some of the biggest loading performance bottlenecks in React apps. How can we optimize them?

🫡 State Management Anti-patterns
React Context and Redux are two of the most common ways to store state in React apps. How to avoid falling into their most common performance traps?

⚛️ React 18 Goodies
How React 18’s features like and useTransition() help to make apps faster.


Main workshop, 4 days: March 12, 13, 16 and 17.
Bonus days: March 19, 20, 23 for Standard + 1 Bonus Day and Standard + 3 Bonus Days participants.
Language: English
Platform: Zoom.
Chat with a speaker: Telegram
Exercises: At the end of each module we will divide into groups to do exercises. To do this, you need to connect from a computer or laptop with Chrome, React DevTools, Git, Node.js, Yarn and your favorite IDE installed.


12.03, Tuesday, 10:00 (GMT+2) - Unnecessary renders (duration ~3 hours)

On day one, we'll dive deep into React's most common performance anti-pattern: unnecessary renders. We'll use Chrome DevTools and React Profiler to profile a slow app and find out what's making it slow. Then, step by step, we will solve each problem we find.

13.03, Wednesday, 10:00 (GMT+2) - Expensive renders (duration ~3 hours)

We'll look at another common React performance problem: expensive renders. We'll see how techniques like virtualization help us deal with large, expensive trees. We'll also look at React 18's startTransition.

16.03, Saturday, 10:00 (GMT+2) – Chains of Renders and Layout Thrashing (duration ~3 hours)

On day three, we'll learn how to recognize, profile, and optimize re-render chains that occur when some code triggers multiple renders in a row. This is common in large single page applications! We'll also explore what happens each time the browser renders a new frame on the screen, and learn what to do when the browser's CSS/layout overhead gets out of hand.

17.03, Sunday, 10:00 (GMT+2) – Hydration (Duration ~3 hours)

Page loading speed is a separate topic that we will not cover in this workshop. However, we'll use everything we've learned so far to dive into a very React-specific load performance issue: the hydration time of server-rendered apps. Expect to see lazy hydration tricks, Suspense and more. We'll also touch a bit on React Server components.

Additional bonus days for Standard + 1 Bonus Day and Standard + 3 Bonus Days ticket members:

19.03, Tuesday, 10:00 (GMT+2) - Bonus Day: Redux Optimizations (Duration ~2 hours)

Not everyone uses Redux. But if you do, chances are Redux is making your app slower. During this bonus day, we'll be looking at a few Redux performance anti-patterns. We'll also learn about different ways to fix them, from writing better selectors and using lesser-known libraries to making architectural changes.

20.03, Wednesday, 10:00 (GMT+2) - Bonus day: Pair coding (Duration ~2 hours)

Time to get your hands dirty! We'll take some slow interactions and optimize them in groups to actually try out what we've learned in practice.

23.03, Saturday, 10:00 (GMT+2)- Bonus Day: Bundle Size (Duration ~2 hours)

Large packages take some time not only to download, but also to compile and run! During this bonus day, let's learn how to analyze your packages and how to deal with problematic dependencies like server modules or icon libraries.


Mid-level or Senior engineers: these folks have solid production React experience and are very familiar with useMemo, useCallback, and React.memo. Still, they would love to get more familiar with Chrome DevTools, React Profiler, and more tools and approaches for diagnosing and debugging React performance issues.

Mentor: Ivan Akulov

—Google Developer Expert

—Web Performance Consultant

—Fullstack programmer.

—Helped many successful startups and companies with Fortune 500: Google, Framer and Appsmith.

—Heads own web performance consulting agency [PerfPerfPerf]

—In addition to work, he explores contemporary art, discovers little-known electronic and techno artists, and is also fond of typography and design.



The course is being held again, we are sharing real reviews from the last time (with the permission of the participants)

"The speaker was going very deep into the audiences questions, which I liked"

"Something I knew but forgot (layout trashing), I learned that first of all we should check dev tools perfomance tab, not use only react profiler, also new for me was that css trick to not render offscreen DOM nodes, and I got understanding of batching in react, I didn't know there was any bathing in react 17. And this library why-did-you-render never heard of that before, cool thing"
"For me personally, each part was the best, a lot of useful information that you can use in your work. I would especially like to note the high-quality study of materials and preparation for the workshop by Ivan Akulov. Thank you to Ivan Akulov for the his work, everything was great."

"I love how Ivan highly explained in detail how chains of re-renders work under the hood and the distinctions between different versions of React. The workshop also gave me a fresh look at the DevTools which overcame my dislike of them!"

"All parts was very useful. But exactly for me was best "Expensive Renders"."

Ticket price


Access to 4 days of the workshop

Access to the workshop recording (for 1 year)

Access to the chat, where the speaker will share links from the workshop

Participation certificate

16 000 UAH ≈€400
till 1 March 8 days left
till 19 February — 14000 UAH≈€350
till 11 March — 18000 UAH≈€450
Buy ticket
Standard + 1 Bonus Day

Access to 4 days of the workshop + any 1 bonus day (to choose)

Access to the workshop and 1 bonus day recordings (for 1 year)

Access to the chat, where the speaker will share links from the workshop

Participation certificate

18 000 UAH ≈€450
till 1 March 8 days left
till 19 February — 16000 UAH≈€400
till 11 March — 20000 UAH≈€500
Buy ticket
Standard + 3 Bonus Days

Access to 4 days of the workshop + all 3 bonus days

Access to the workshop and all 3 bonus days recordings (for 1 year)

Access to the chat, where the speaker will share links from the workshop

Participation certificate

20 000 UAH ≈€500
till 1 March 8 days left
till 19 February — 18000 UAH≈€450
till 11 March — 22000 UAH≈€550
Buy ticket

Fwdays is Ukrainian company, that is why payment for services is made in the national currency of Hryvnia. You can see the approximate price in Euros at blocks with the price.

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