Optimistic UI makes apps feel instant by showing results before the server confirms them. In most apps that's a fine trade-off. In financial applications, showing a user an incorrect balance even for 200ms is a trust problem that compounds. This talk explores the tension between perceived performance and correctness, the React patterns that resolve it, and why "optimistic" is a UX promise your architecture needs to be able to keep.
This talk has been presented at React Advanced 2026, check out the latest edition of this React Conference.




















