I've spent a lot of time debugging and doing performance optimization investigations throughout my career. It's second nature to me at this point, but a lot of developers have never really tried to investigate app performance.

In late 2025 I spent multiple months investigating and optimizing performance in the Immer immutable update library.

This talk covers how to approach performance investigation with a scientific approach mindset. It covers key investigation approach concepts, common perf profiling and visualization tools, and techniques to optimize code to run faster, and uses experiences from my Immer work as practical examples.

React Paris 2026 🔗︎

How I Made Immer Twice as Fast: slides 🔗︎

This is a post in the Presentations series. Other posts in this series:

• Mar 26, 2026 - Presentations: How I Made Immer Twice as Fast: Performance Optimization in Practice
• Jun 13, 2025 - Presentations: The State of React and the Community in 2025
• Nov 21, 2024 - Presentations: Maintaining a Library and a Community
• Nov 21, 2024 - React Advanced 2024: Designing Effective Documentation
• Jul 09, 2024 - React Summit 2024: Why Use Redux Today?
• Nov 13, 2023 - React Summit US 2023: What's New in Redux Toolkit 2.0
• Oct 24, 2023 - React Advanced 2023 - Building Better React DevTools with Replay Time Travel
• Aug 16, 2023 - React Rally 2023 - A (Brief) Guide to React Rendering Behavior
• Jun 01, 2023 - Presentations: Debugging JavaScript
• Dec 11, 2022 - Presentations: 2022 Podcasts
• Jun 27, 2022 - Presentations: Modern Redux with Redux Toolkit
• May 04, 2022 - Reactathon 2022: The Evolution of Redux Async Logic
• May 04, 2022 - TS Congress 2022: Lesson from Maintaining TS Libraries
• May 29, 2021 - Presentations: Learn Modern Redux Livestream
• May 29, 2021 - Presentations: The State of Redux, May 2021
• May 29, 2021 - Presentations: Podcast Appearances in 2021
• May 25, 2021 - Presentations: Using Git Effectively
• Dec 20, 2020 - Presentations: Intro to React, Redux, and TypeScript (2020)
• Dec 03, 2020 - Presentations: Podcast Appearances in 2020
• Oct 08, 2020 - Global React Meetup: The State of Redux 2020
• Oct 19, 2019 - Git Under the Hood: Internals, Techniques, and Rewriting History
• Sep 24, 2019 - React Boston 2019: Hooks, HOCs, and Tradeoffs
• Jun 11, 2019 - ReactNext 2019: A Deep Dive into React-Redux
• May 22, 2019 - Presentation: JavaScript for Java Devs
• Mar 31, 2019 - Reactathon 2019 Keynote: The State of Redux
• Oct 01, 2018 - React Boston 2018 Presentation: The State of Redux
• Jun 30, 2018 - Redux Fundamentals Workshop Slides
• Mar 20, 2018 - Reactathon Presentation: Redux Fundamentals
• Mar 07, 2018 - Presentation: Intro to React and Redux (March 2018)
• Sep 24, 2017 - React Boston 2017 Presentation: You Might Need Redux (And Its Ecosystem)
• Feb 24, 2017 - Presentation Sources Published
• Feb 17, 2017 - Presentation: Intro to React and Redux
• Oct 07, 2016 - Presentation: Modern Web Dev Overview