Deep Diving on Concurrent React
summary
Concrete description of how React 18 schedules work: the scheduler yields back to the browser roughly every 5ms so renders become interruptible; updates map to 31 render lanes using bitmasks so batching and priority are explicit; transitions mark non‑urgent UI updates (wrap setState with startTransition) and Suspense SSR streams interactive islands to improve FCP and INP; ecosystem tooling includes the isInputPending check and a postTask‑style prioritized task API under discussion.
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chapters (10)
- 0:00Introduction and setup
- 2:14Main thread bottlenecks
- 4:42Parallelism vs concurrency
- 9:15Scheduling in React
- 13:53Practical scheduling benefits
- 17:25Tackling wasted renders
- 19:09Suspense SSR improvements
- 21:15Profiler enhancements
- 23:01Future of scheduling APIs
- 28:15Closing notes and Q&A
