With the proliferation of React applications in the wild, I thought it would be a good idea to examine some techniques for evaluating the performance of React Components.

React is frequently touted as being performant due to the optimizations of its Virtual DOM technique, yet all to often this is used by developers as a crutch to avoid thinking about the performance of their code at all. This generally leads to performance problems in React apps of any significant scale.

This screencast covers a number of techniques for constructing components, but also shows how to evaluate performance objectively and make informed refactoring decisions.

Screencast Outline

  1. Introduction

    • A Common UI Scenario for React Components -> Large Data Tables
    • Developer Default: Google/Stack Overflow Driven Development
    • The Quest for a pre-built Library
  2. Performance Goals

    • Important Metrics: TTI (time to interactive), TTFMP (time to first meaningful paint)
    • Setting a Frame Budget: (60fps / 16.7ms) might not always be feasible
    • The Feedback Loop: Experiment, Evaluate
  3. React Development Patterns

    • Start BIG: 1 component, 1 render method, then profile
    • Decompose: limit the surface area of your component by thinking hard about props, then profile
    • Optimize by:
      • Reducing JS Execution: work the browser doesn't have to do doesn't need to be optimized
      • Reducing Surface Area for Change: small components, limited surface area, small lists of props
      • Keep render methods simple and mostly static



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