React in Depth: Rendering, State and Suspense
Stop fighting re-renders. Understand the model well enough to predict them.
Mara Velasco
Principal engineer · 12 years shipping web platforms
- Performance
- React
- TypeScript
What you will be able to do
- Predict exactly when and why a component re-renders
- Use effects for synchronisation rather than as lifecycle hooks
- Model state so derived values never drift out of sync
- Apply Suspense and transitions to real data loading
- Profile a slow tree and fix the actual cause
About this course
This is the course for people who can already build with React and keep getting surprised by it. We go through the render model, reconciliation, effects as a synchronisation tool rather than a lifecycle hook, and the concurrent features that changed how data loading works. Every module ends with a real refactor of a component that was slow or wrong for a reason you can now name.
Curriculum
3 sections · 9 lessons
- 1Render, commit, and the two phasesWhy your console.log fires twice and what that tells you.Preview21 min
- 2Reconciliation and keysThe diffing rules, and the bug keys are actually there to prevent.18 min
- 3Why memo usually does nothingThe three conditions all of which must hold for memo to help.16 min
Before you start
- Comfortable building components with hooks
- Working knowledge of JavaScript closures
Student reviews
4.5 from 4
Sofía Marchetti
19 Aug 2026Solid content, pacing is uneven
The first and last modules are outstanding. The middle one felt rushed relative to how important it is. Still recommend it, with that caveat.
5 found this helpful
Léo Fontaine
19 Aug 2026Changed how my team works
I ran the middle section as a lunch-and-learn series with my team. We have since adopted three of the practices as defaults. Rare for a course to have that effect.
27 found this helpful
Amara Diallo
19 Aug 2026Changed how my team works
I ran the middle section as a lunch-and-learn series with my team. We have since adopted three of the practices as defaults. Rare for a course to have that effect.
13 found this helpful
Hana Kimura
19 Aug 2026Finally, the why and not just the how
I have taken four courses on this topic and this is the first one that explained the underlying model instead of walking me through syntax. The section on validation alone changed how I work.
15 found this helpful