Aliaksei Kuncevič

Angular Consultant @

How to improve the performance of a Single Page Application

by Aliaksei Kuncevič




Research on U.S. Net habits suggests that if this sentence takes longer than a second to load, many citizens will have clicked elsewhere already. If you’ve got the patience (or are European) read on for more shocking data on not dawdling. (c)

How 1 second could cost Amazon $1.6 billion in sales

Keep Site Speed Below 2-3 Seconds (c) Google

SPA life cycle

Page load timeline

Should you measure only page load time?

Other Key Metrics

  • Start render time (First paint)
  • First contentful paint
  • First meaningful paint
  • Time to interactive


How do we improve the performance metrics?

Basic techniques

  • Minification, uglification
  • Code splitting (Lazy loading)
  • Data urls
  • PWA
  • Images compressing

Advanced techniques

  • App Shell Pattern
  • Tree shaking (rollup)
  • Bundle size optimization
  • Closure compiler

Angular 2/4/5/6/7(beta)

  • Minification, uglification
  • Code splitting (Lazy loading)
  • Data urls
  • PWA
  • Tree shaking (rollup)
  • Bundle size optimization

Bafore vs After


How do we measure performance time metrics?

Chrome dev tools


Lighthouse Report

Performance browser API

  • Performance observer
  • High resolution time
  • Performance entry

Other techniques

  • Server-side rendering (SSR/Universal)
  • Prerendering


  • Minimize the assets (Minify, uglify, compress)
  • Optimize bundles (Tree shake, inspect manually)
  • Ship less JavaScript (Lazy load)
  • Remove render blocking scripts from the <head>


questions ?