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Speed is Essential for a Great Web Experience (oredev)
- Speed is Essential for a Great Web Experience @andydavies #oredev Nov 2012 http://www.flickr.com/photos/dex1138/7879381800
- Performance isn’t always a priority http://www.flickr.com/photos/randomidea/247994072
- “Has it loaded yet?” http://www.flickr.com/photos/kindofindie/4099768084
- Our perception of response time Instant Seamless Yawn! 100ms 1s 10s 3s - Recommended 6.5s - Alexa 2000 Load Time Fall 2012 Response Time in Man-computer Conversational Transactions Robert B. Miller, 1968
- “50% more concentration when using badly performing web sites” Foviance http://www.flickr.com/photos/yourdon/3366991042
- Effect of delay on abandonment rate... Abandonment rate over 200+ sites / 177+ million page views over 2 weeks - http://www.measureworks.nl / Gomez
- Bing did some experiments +1s $/ - 2.8% +
- Wallmart made some improvements -1s +2%
- Shopzilla cut page load time by 5 seconds! +12% +25% -50% $$$ http://velocityconf.com/velocity2009/public/schedule/detail/7709
- Measuring page load time... http://www.flickr.com/photos/wwarby/7109538317
- W3C Navigation Timing API navigaAonStart, redirectStart, redirectEnd, fetchStart, domainLookupStart, domainLookupEnd, connectStart, (secureConnecAonStart), connectEnd, requestStart, responseStart, responseEnd, Prompt, App, for, redirect, DNS, TCP, Request, Response, Processing, onLoad, cache, unload, unload, loadEventEnd, loadEventStart, domComplete, domContentLoaded, domInteracAve, domLoading, unloadEnd, unloadStart, http://www.w3.org/TR/navigation-timing/
- Navigation Timing Data in Google Analytics Text Other Real User Monitoring tools available
- Example of Real Users Experience 27% Visitors (%) 13% 8% 8% 6% 6% 3% 3% 2% 1% 1 2 3 4 5 6 7 8 9 10 Load Time (s)
- Example of Real Users Experience 27% 24% Visitors (%) 13% 8% 8% 6% 6% 3% 3% 2% 1% 1 2 3 4 5 6 7 8 9 10 > 10 Load Time (s)
- Synthetic Monitoring 3 Response Time (s) 2 1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 16 27 28 29 30 September 2012
- Examining the detail... http://www.flickr.com/photos/arnybo/2679622216
- Browser Plugins YSlow PageSpeed
- webpagetest.org
- Waterfall for bbc.co.uk/news
- mobitest.akamai.com Alternatively, could use Chrome / Safari remote debugging to generate HAR
- Bigger, Faster Servers? http://www.flickr.com/photos/getbutterfly/6317955134
- Over 80% 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 2 3 4 5 Measured via residential ADSL line using Google Chrome
- But don’t forget to fix slow server responses 4 seconds!
- 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)
- “More Bandwidth Doesn’t Matter (much)” Mike Belshe 3.11s Page Load Time 1.95s 1.63s 1.50s 1.44s 1.41s 1.39s 1.38s 1.37s 1.36s 1 2 3 4 5 6 7 8 9 10 Bandwidth (Mbps)
- Visualising TCP Carlos Bueno (@archivd) https://vimeo.com/14439742
- Impact of Latency 4 3 Page Load Time (s) 2 1 0 20 40 60 80 100 120 140 160 180 200 220 240 Round Trip Time (ms)
- 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
- Latency is Our Biggest Enemy “In 2012, the average worldwide RTT to Google is still ~100ms, and ~50-60ms within the US.” “we are looking at 100-1000ms RTT range on mobile” Ilya Grigorik http://www.igvita.com/2012/07/19/latency-the-new-web-performance-bottleneck/
- 3G Radio Resource Control Idle for 12s IDLE CELL_FACH 1s delay 1-2s delay! CELL_DCH Idle for 5s Exact timings vary and depend on carrier NOT device http://web.eecs.umich.edu/~fengqian/paper/3g_imc10.pdf
- Going Faster… http://www.flickr.com/photos/mikebaird/2464769129/
- Speeding Things Up - Some Basics ★ Compress ★ Minify ★ Reduce Requests ★ Cache ★ HTTP Keep-Alive ★ Use a CDN?
- What’s the web made of? Images Scripts Stylesheets HTML Flash Other Composition of ‘average’ web page via httparchive.org
- Bitmapped Images JPEG PNG GIF Optimise, Optimise, Optimise! (jpegmini, pngmini, Smush.it, ImageOptim, Gifsicle etc.)
- New Devices, New Challenges... 2 x Resolution = 4 x Pixels! http://www.flickr.com/photos/roopaw/6985954465
- Some Alternatives CSS SVG Fonts Bitmaps still a challenge but interesting experiments around
- It’s no longer a desktop world http://www.flickr.com/photos/adactio/6960610178
- Go “Mobile First” for Responsive Designs http://seesparkbox.com
- Use “Right-sized” Images http://www.flickr.com/photos/emzee/139794246 Standards support (picture? srcset?) is coming but unclear when! Meanwhile services such as sencha.io, resrc.it and JS libraries - picturefill.js, foresight.js can help.
- Minimise browser blocking... http://www.flickr.com/photos/barteko/6128499314
- Parallel Downloads news.bbcimg.co.uk static.bbc.co.uk Domain Sharding increases number of parallel downloads but… …more connections may not be a good idea on mobile …may also interfere with multiplexing in protocols like SPDY
- 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> * Depends on size and whether major / minor breakpoints used
- Load remaining Javascript late as possible . . . <script src="restofscript.js"></script> </body> </html> One file or many? (Depends on size) Script loaders can help but scripts aren’t discoverable by pre-fetcher
- The Script Tag <script src=″…″></script> Until the script has executed, the rendering of all elements below is blocked!
- “Virgin Media Broadband ISP Users Affected by Website Routing Woes” ISP Review, May 26, 2012 Customer jcmm33 said: “Same issue here as well, been like this all day. Sites like autotrader.co.uk don’t appear to be accessible, others like the telegraph.co.uk are waiting on other components to download (content from sites like cg-global.maxymiser.com, pixel.quantserve.com).” http://www.ispreview.co.uk/index.php/2012/05/uk-virgin-media-broadband-isp-users-affected-by-website-routing-woes.html
- Impact on The Telegraph… Same issue affected many other sites http://bit.ly/Ncy7Rd
- 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> Or use a script loader - labjs, requirejs, yepnope etc.
- Lots of factors to think about... http://www.flickr.com/photos/corneveaux/3248566797
- Don’t have to do it all by hand http://www.flickr.com/photos/simeon_barkas/2557059247
- Performance isn’t just for Christmas Measure Optimise Analyse
- Measure Impact on Business Goals http://www.flickr.com/photos/safari_vacation/5961260280
- http://www.flickr.com/photos/jurvetson/6212582593
- @andydavies andy@asteno.com http://www.slideshare.net/andydavies http://www.flickr.com/photos/auntiep/5024494612
- Credits All photographs copyright original owners on flickr.com Following pictograms courtesy of The Noun Project