React Performance Debugging

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Ivan’s first attempts at performance debugging were chaotic. He would see a slow interaction, try a random optimization, see that it didn't help, and keep trying other optimizations until he found the right one (or gave up).


Back then, Ivan didn’t know how to use performance devtools well. He would do a recording in Chrome DevTools or React Profiler, poke around it, try clicking random things, and then close it in frustration a few minutes later. Now, Ivan knows exactly where and what to look for. And in this workshop, Ivan will teach you that too.


Here’s how this is going to work. We’ll take a slow app → debug it (using tools like Chrome DevTools, React Profiler, and why-did-you-render) → pinpoint the bottleneck → and then repeat, several times more. We won’t talk about the solutions (in 90% of the cases, it’s just the ol’ regular useMemo() or memo()). But we’ll talk about everything that comes before – and learn how to analyze any React performance problem, step by step.


(Note: This workshop is best suited for engineers who are already familiar with how useMemo() and memo() work – but want to get better at using the performance tools around React. Also, we’ll be covering interaction performance, not load speed, so you won’t hear a word about Lighthouse 🤐)

This workshop has been presented at React Advanced 2023, check out the latest edition of this React Conference.

FAQ

The instructor is Ivan Akulov, a Google Developer Expert and web performance engineer with over five years of experience working with companies like Framer, Google, and CNBC.

The workshop lasts for three hours, including 10-minute breaks every hour.

If you have any questions during the workshop, you can post them in the chat, and the instructor will respond. There will also be a Q&A session at the end of the workshop.

You can follow the link provided by the instructor (https://bit.ly/Reaperfnotes) to access a Google document for collaborative note-taking.

The workshop is divided into three parts: 1. Focusing on Chrome DevTools and indirect profiler. 2. Debugging a large real-world app. 3. Debugging effects and using additional tools like useRateAgeUpdates and Console.Time.

To debug a slow interaction, you can start by recording the interaction using Chrome DevTools, checking whether most of the time is spent in React code, and then using React Profiler to identify the most expensive components. Tools like 'why-did-you-render' can help identify why components re-render.

You can optimize a React app by identifying and memoizing expensive components, using tools like React Profiler and 'why-did-you-render' to find components that re-render unnecessarily, and applying techniques like debouncing expensive functions.

When profiling performance, check whether the time is spent in React rendering or in React effects. Use Chrome DevTools to find expensive components and effects, and validate findings with React Profiler and 'why-did-you-render'.

The workshop utilizes tools such as Chrome DevTools, React Profiler, and the library 'why-did-you-render' for debugging performance issues in React applications.

The 'why-did-you-render' library helps identify why a React component re-renders by showing changes in hooks, props, and state, making it easier to debug performance issues.

Ivan Akulov
Ivan Akulov
148 min
31 Oct, 2023

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Video Summary and Transcription
This Workshop on React Performance Debugging covers various topics such as analyzing performance with Chrome DevTools and React Profiler, optimizing components to improve performance, and debugging performance issues with tools like Why Did You Render and console.time. It also emphasizes the importance of prioritizing performance and fostering a performance-oriented culture within development teams. The Workshop concludes with insights on monitoring and optimizing React performance, including challenges with third-party libraries and the limitations of the React Fiber compiler.
Video transcription and chapters available for users with access.

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Back then, Ivan didn’t know how to use performance devtools well. He would do a recording in Chrome DevTools or React Profiler, poke around it, try clicking random things, and then close it in frustration a few minutes later. Now, Ivan knows exactly where and what to look for. And in this workshop, Ivan will teach you that too.
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