Chapter 23 Performance

Transform your poor-performing prototype app into a fast one capable of handling thousands to tens of thousands of users simultaneously.

Learning Objectives

• Benchmark your app using the shinyloadtest package to simulate multiple users.
• Audit your app with the Google Lighthouse node.js package to evaluate front-end performance.
• Profile your app to identify performance bottlenecks:
  • Use the profvis package to pinpoint slow R code.
  • Use shiny.tictoc JavaScript to measure:
    • Time spent on server-side calculations
    • Time needed to recalculate outputs
• Optimize your code by:
  • Moving data preparation code outside the app
  • Making the code faster
  • Caching reactives and outputs
  • Applying psychological principles to make your app feel faster