Mark Erikson

Mark Erikson is a Senior Engineer at Replay, and lives in southwest Ohio, USA. Mark is a Redux maintainer, creator of Redux Toolkit, and general keeper of the Redux docs. He tweets on BlueSky at @acemarke.dev, and blogs at https://blog.isquaredsoftware.com. He spends much of his time answering questions about React and Redux anywhere there's a comment box on the internet, and usually hangs out in the Reactiflux chat channels.

Replay.io, USAblog.isquaredsoftware.com acemarke markerikson acemarke.dev

How I Made Immer Twice as Fast: Performance Optimization in Practice

React Summit US 2026

Upcoming

How I Made Immer Twice as Fast: Performance Optimization in Practice

We all want software to run fast, and "performance" can include everything from network times to keyboard latency. But what about when you really do need Blazing Fast (TM) CPU speed from your code? How do you know what sections of your code are slow, _why_ it's slow, and how to make it faster?

Like writing code and debugging, performance optimization is a skill set that anyone can (and should!) learn. We'll look at key concepts and approaches for profiling and optimizing CPU-level code performance, using real-world examples based on my experience optimizing the widely-used Immer JS library.

You'll learn how to set up reliable benchmarks, capture profiles and interpret flame charts, identify hotspots in your code, and apply optimizations ranging from simple wins like local caching to larger architectural changes. These techniques can help any developer's code run faster!

performance