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Web Performance Optimization


Overview on why web performance matters, how to measure it and some discussion on 3rd-party content. …

Overview on why web performance matters, how to measure it and some discussion on 3rd-party content.

Presented t the DC area Web Manager's Roundtable group on 12/7/2011.

Published in Technology , Design
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  • 1. Web Performance OptimizationPatrick
  • 2. What is it?• Optimizing the performance of web sites and applications for the best user experience
  • 3. Why it matters…
  • 4. Bing Search
  • 5. Google Search
  • 6. Yahoo 400ms slower = 5-9% drop in full-page traffic
  • 7. Firefox Downloads …shaved 2.2 seconds off the average page load time and increased download conversions by 15.4%!
  • 8. Shopzilla (e-Commerce)
  • 9. Netflix
  • 10. MSNDelayed loading of the Big Upper Right Ad by 1s Time to Page Time to Page Page Ad Click Thru Bottom Onload Clicks Views Rate 80ms gain 500ms gain +0.5% +0.4% -15%
  • 11. AutoAnything …cut AutoAnything’s web page load times in half, which resulted in a 9% increase in conversion rate, an 11% increase in average ticket size, and a 12-13% increase in sales.
  • 12. Sports Reference
  • 13. SEO …weve decided to take site speed into account in our search rankings.
  • 14. “Front End” vs“Back End”
  • 15. Back-EndThis is the HTML that largely contains the content of thepage and defines the structure.
  • 16. Front-End CSS : Layout and style Graphical ElementsImages
  • 17. Waterfall DiagramBase Page CSS Javascript Images and Graphical Elements Start Render Document Complete (onLoad)
  • 18. MeasuringPerformance
  • 19.
  • 20. Active Testing• Consistent results • Good for detecting and diagnosing issues that are 100% repeatable and on pages you are monitoring• Lots of detail• Availability monitoring• Not representative of actual end-user performance • Usually tested from data centers • Sometimes co-located with CDN provider equipment
  • 21. Synthetic Browsers• Know HOW your active testing is done • Some only test the base page • Synthetic browsers usually not reflective of real browser • Real browser testing• • Synthetic Browser: 447 requests • IE 8: 241 requests
  • 22. Real User Monitoring (RUM)• Full coverage on all pages visited by users• Real performance information for end-user experience• No availability monitoring• Fluctuates Significantly• Limited detail • … but getting better
  • 23. _gaq.push([_setSiteSpeedSampleRate, 10]);
  • 24. Back-End Only
  • 25. Async JavascriptIt’s not just good for performance….
  • 26. Frontend Single Point of Failure Browser will stop processing for 20s (windows) – 90s (Mac)<script type="text/javascript" src=""></script> vs. <script type="text/javascript"> (function() { var tw = document.createElement(script); tw.type = text/javascript; tw.src =; var s = document.getElementsByTagName(script)[0]; s.parentNode.insertBefore(tw, s); })(); </script> Browser will continue processing and not wait
  • 27. What it feels like
  • 28. Testing for Frontend SPOF• (aka• Hosts file: 31 …• setDnsName navigate
  • 29.• If AddThis or Ensighten have issues
  • 30.• If Google’s APIs have issues
  • 31.• If Doubleclick has issues First 20 seconds 20-40 seconds
  • 32.• If Doubleclick has issues
  • 33. Other Resources• Velocity Conference videos and presentations: • • •• Perf Planet (rollup of industry blogs) • • • @perfplanet