Web Performance

You don't need scientific research to understand the importance of fast responding website. The Yahoo team has identified 35 best practices to make web pages fast.

Content

  • Make Fewer HTTP Requests.
  • Reduce DNS Lookups.
  • Avoid Redirects.
  • Make Ajax Cacheable.
  • Postload Components.
  • Preload Components.
  • Reduce the Number of DOM Elements.
  • Split Components Across Domains.
  • Minimize Number of iframes.
  • Avoid 404s.

Server

  • Use a Content Delivery Network (CDN).
  • Add Expires or Cache-Control Header.
  • Gzip Components.
  • Configure ETags.
  • Flush Buffer Early.
  • Use GET for Ajax Requests.
  • Avoid Empty Image src.

Cookie

  • Reduce Cookie Size.
  • Use Cookie-Free Domains for Components.

CSS

  • Put Stylesheets at Top.
  • Avoid CSS Expressions.
  • Choose Over @import.
  • Avoid Filters.

JavaScript

  • Put Scripts at Bottom.
  • Make JavaScript and CSS External.
  • Minify JavaScript and CSS.
  • Remove Duplicate Scripts.
  • Minimize DOM Access.
  • Develop Smart Event Handlers.

Images

  • Optimize Images.
  • Optimize CSS Sprites.
  • Do Not Scale Images in HTML.
  • Make favicon.ico Small and Cacheable.

Mobile

  • Keep Components Under 25 KB.
  • Pack Components Into a Multipart Document.

The full document available on the Yahoo Developer Network