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Speed is Essential for a Great Web Experience (Canvas Conf Version)

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Speed is Essential for a Great Web Experience (Canvas Conf Version)

  1. Speed is Essential for a Great Web Experience @andydavies #CanvasConf Sep 2012 http://www.flickr.com/photos/barkaway/342359810
  2. But sometimes other concerns take priority... http://www.flickr.com/photos/randomidea/247994072
  3. “Are we there yet?” http://www.flickr.com/photos/sharynmorrow/643126727
  4. Our perception of response time Instant Seamless Yawn! 100ms 1s 10s 3s - Recommended 7s - Fortune 500 Load Time Average (2010) Response Time in Man-computer Conversational Transactions Robert B. Miller, 1968
  5. “50% more concentration when using badly performing web sites” Foviance http://www.flickr.com/photos/yourdon/3366991042
  6. Effect of delay on abandonment rate... Abandonment rate over 200+ sites / 177+ million page views over 2 weeks - http://www.measureworks.nl / Gomez
  7. Bing did some experiments +1s $/ - 2.8% +
  8. Wallmart made some improvements -1s +2%
  9. Shopzilla cut page load time by 5 seconds! +12% +25% -50% $$$ http://velocityconf.com/velocity2009/public/schedule/detail/7709
  10. Measuring page load time...
  11. Measure Real Users’ Experience 27% 24% of visitors 24% waited over 10s Visitors (%) 13% 8% 8% 6% 6% 3% 3% 2% 1% 1 2 3 4 5 6 7 8 9 10 > 10 Load Time (s)
  12. Measuring Real Users - Google Analytics Relies on Navigation Timing API, can add extra timing calls to page
  13. Measuring Real Users - LogNormal
  14. Measuring Real Users - Torbit Insight
  15. Measuring Real Users - New Relic
  16. webpagetest.org
  17. Waterfall for bbc.co.uk/news
  18. mobitest.akamai.com
  19. Bigger, Faster Servers? http://www.flickr.com/photos/br1dotcom/4297736794
  20. 80% plus of page load time is on front-end Backend news.bbc.co.uk Frontend ebay.co.uk debenhams.co.uk direct.gov.uk amazon.co.uk mumsnet.com guardian.co.uk 0 1.25 2.5 3.75 5 Measured on residential ADSL line using Chrome 19
  21. Fix slow server responses first 4 seconds!
  22. Bandwidth (often) isn’t the bottleneck 2.0 1.5 1.0 0.5 0s 5s 10s news.bbc.co.uk tested via webpagetest.org throttled at 1.5Mbps (bursts over 1.5Mbps are artefact of testing)
  23. Minimum round trips to download a file (TCP Segments) 285kB 214kB 143kB 71kB Size 1 2 3 4 5 6 7 8 9 10 11 Round Trips TCP and the Lower Bound of Web Performance John Rauser
  24. Going Faster… http://www.flickr.com/photos/mikebaird/2464769129/
  25. Get the <head> straight <!doctype html> <html> <head> CSS before JS <meta charset="utf-8"> Ideally one file* <title>This is my title<title> <link rel="stylesheet" href="styles.css" type="text/css" /> <script src="script.js"></script> . . Only JS needed . during page load </head> * Bryan and Stephanie Rieger’s major and minor breakpoint approach requires multiple CSS files
  26. Load remaining Javascript late as possible . . . <script src="restofscript.js"></script> </body> </html> One file or many? (Depends on size) Could you defer some JS until after onload?
  27. Squash text based content - gzip / minify http://www.flickr.com/photos/evdg/298415813
  28. Images are 64% of an ‘average’ web page http://www.flickr.com/photos/zaprittsky/4520788183/
  29. Bitmapped Images JPEG PNG GIF Optimise, Optimise, Optimise! (jpegmini, pngmini, Smush.it, ImageOptim, Gifsicle etc.)
  30. New Devices, New Challenges... 2 x Resolution = 4 x Pixels! http://www.flickr.com/photos/roopaw/6985954465
  31. Some Alternatives CSS SVG Fonts Watch SVG - may not always be smaller than bitmap!
  32. Re-use TCP Connections via HTTP Keep-Alive Orange segments are TCP connections being (re-) opened
  33. news.bbcimg.co.uk static.bbc.co.uk Increase number of parallel downloads
  34. Sometimes... The Waterfall of Doom! 2 seconds! (nearly)
  35. Reduce number of HTTP requests
  36. Cache resources that don’t change ‘often’ forever (use versions to replace) http://www.flickr.com/photos/sterlingely/64228609
  37. Redirects - necessary but waste time… Why 2 redirects? Expensive over mobile networks due to latency
  38. The Perils of Third Party Javascript... “Virgin Media Broadband ISP Users Affected by Website Routing Woes” ISP Review, May 26, 2012 cg-global.maxymiser.com unreachable
  39. Impact on The Telegraph… Same issue affected many other sites http://bit.ly/Ncy7Rd
  40. Load Third Party scripts asynchronously <script type="text/javascript"> function() { var js = document.createElement('script'); js.async = true; js.src = 'myscript.js'; var e = document.getElementsByTagName('script')[0]; e.parentNode.insertBefore(js, first); })(); </script> async attribute may be option but not supported by IE & Opera
  41. Argh... My brain hurts! http://www.flickr.com/photos/corneveaux/3248566797
  42. Don’t have to do it all by hand http://www.flickr.com/photos/simeon_barkas/2557059247
  43. Performance isn’t just for Christmas Measure Optimise Analyse
  44. http://www.flickr.com/photos/jurvetson/6212582593
  45. @andydavies andy@asteno.com http://www.slideshare.net/andydavies http://www.flickr.com/photos/auntiep/5024494612
  46. Credits All photographs copyright original owners on flickr.com Following pictograms courtesy of The Noun Project

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