Tuesday, November 13, 2012


This was a far better session although 3 hours without a coffee break (and a smoke) was really long. Big websites like Google try to meet the following rule of thumb: page loads should stay under 250 milliseconds. Page loads between 100 and 300 milliseconds are considered sluggish and if they last longer than 10 seconds, the user gives up. The speaker went a long way explaining how browsers work and how they can help us to achieve better page loads. An overview of actions that may help: reduce the number of DNS lookups, avoid redirects (like our dashboard redirect for instance), make fewer HTTP requests, use a CDN, GZIP assets, optimize images, add an Expires header, add ETags, put the CSS at the top, use async scripts (scripts that do a document.write block the DOM construction), place the scripts at the bottom, minify + concatenate.  He also showed us how useful some tools can be like PageSpeed Insights. 


  1. "The Chrome Dev Tools can to THAT" was probably a condensed version of this talk that focused on the dev tools available in the Chrome browser. It is impressive to see how much information is now available to analyze client side performance in the browser: up to the frames_per_second rendering level. Although I wonder, if you're going this deep, are possible optimizations still valid or even beneficial in all browsers.

  2. The presentation slides are available at: http://www.igvita.com/slides/2012/webperf-crash-course.pdf


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