ReactFoo Delhi

ReactFoo Delhi

On React, performance and front-end engineering

Punit Sethi


Improving React App Performance : A Case Study

Submitted Jul 18, 2019

This talk is about our experience of performance optimizing our React App. Objective of our exercise was to quantifiably improve our app’s performance in a few (4-6) weeks. This presentation details how we measured the gains and what React + Webpack changes we leveraged to achieve the gains.

Front-end devs wanting to improve their React SPA performance shall find this talk insightful. Key take-aways:
- what are the Webpack & React performance optimization options avaialable
- how to apply those optimizations
- how to make performance optimization exercise effective

Few tools I intend to talk about are Webpack Bundle Analyzer, Chrome Devtools, WebpageTest. Few optimization capabilities I shall disccuss are related to tree shaking, code splitting, dynamic library loading, babel-preset-env, vendor bundle webpack configuration, brotli, etc.


  • How we measured our React App’s performance & improvement
  • Performance metrics
  • Test conditions
  • Tools

  • How we improved our React App’s performance

  • Identified & removed unused libraries / part of libraries
  • Code splitting with React’s lazy & suspense
  • Identify & load specific libraries libraries dynamically
  • Reduce babel transpiled code with babel-preset-env
  • Reduce download size with brotli-webpack-plugin

  • Details of Performance Improved

  • Timings
  • Size of our JS Bundles



Speaker bio

Punit Sethi is founder of Tezify. offers tools & services to measure & improve front-end performance. Punit has worked on improving performance of various high-traffic Indian ecommerce websites. Prior to Tezify, Punit has been working on software performance for a decade.




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