Are Today’s Good Practices... Tomorrow’s Performance Anti-Patterns?
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![Yet, this is how we typically asynchronously load scripts
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Saturday, 19 October 13](https://image.slidesharecdn.com/velocity-nyc-131019050709-phpapp02/75/are-todays-good-practices-tomorrows-performance-antipatterns-18-2048.jpg?cb=1668706736)
Are Today’s Good Practices... Tomorrow’s Performance Anti-Patterns?
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The web is ever changing… browsers are evolving, new protocols are emerging and mobile continues its relentless rise. We’re already starting to bend some of the original performance rules and as the web changes further will our current good practices last, or will some become barriers that hinder performance?
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Are Today’s Good Practices... Tomorrow’s Performance Anti-Patterns?
- 1. Are Today’s Good Practices… Tomorrow’s Performance Anti-Patterns? @andydavies #VelocityConf, New York http://www.flickr.com/photos/nzbuu/4093456029 Saturday, 19 October 13
- 2. What if … … dataURIs are an anti-pattern? http://www.flickr.com/photos/willypayne/3116395089 Saturday, 19 October 13
- 4. dataURIs for CSS images Makes a blocking resource larger by including non-blocking resources • Browser can’t start rendering page until CSS has downloaded * • Images don’t block Do they have the same caching lifetime? * Some browsers defer download of CSS when media query doesn’t match Saturday, 19 October 13
- 5. 1. Take 50 icons 2. Create 50 stylesheets, each with one more dataURI than previous 3. Create matching HTML file for each stylesheet 4. Test them all! Saturday, 19 October 13
- 6. Larger CSS download == longer time to RenderStart RenderStart - TTFB (ms) 1000 875 750 625 500 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 Number of Sprites Saturday, 19 October 13
- 7. We have our rules… http://www.flickr.com/photos/sowrey/2441134911 Saturday, 19 October 13
- 8. and we love recipes… http://www.flickr.com/photos/mrsmagic/2247364228 Saturday, 19 October 13
- 9. But, what happens when things change? Saturday, 19 October 13
- 10. Browsers already use the network differently Saturday, 19 October 13
- 11. Saturday, 19 October 13
- 12. Saturday, 19 October 13
- 13. New network protocols are coming here http://www.flickr.com/photos/jonlachance/3427660741 Saturday, 19 October 13
- 14. Differences in TCP Connection Use HTTP 1.1 SPDY Saturday, 19 October 13
- 15. New Standards - opportunities and challenges Saturday, 19 October 13
- 16. How much do we rely on inline JavaScript? http://www.flickr.com/photos/jfraissi/6352877711 Saturday, 19 October 13
- 17. 74% of visitors support async attribute <script async src="myscript.js"><script> http://caniuse.com/script-async Saturday, 19 October 13
- 18. Yet, this is how we typically asynchronously load scripts <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> Saturday, 19 October 13
- 19. XSS Saturday, 19 October 13
- 20. Content-Security-Policy “Content Security Policy, a mechanism web applications can use to mitigate a broad class of content injection vulnerabilities, such as cross-site scripting (XSS)” http://www.w3.org/TR/CSP/ Saturday, 19 October 13
- 21. Example Only allow scripts to be executed if they come from a designated host, disables inline scripts by default. Content-Security-Policy: script-src http://www.site.com Can re-enable inline scripts, but increases XSS risk Content-Security-Policy script-src 'self' Saturday, 19 October 13
- 22. What other performance enhancements do we rely on JS for? Guardian split page into - Content - Enhancements - Leftovers Others rely on scroll handlers for lazyload Saturday, 19 October 13
- 23. Tested some scenarios, measured the outcomes http://www.flickr.com/photos/chandramarsono/4324373384 Saturday, 19 October 13
- 24. Test Environment - EC2 - Medium Instance - Dublin - Apache 2.2 - GZIP - Keep-Alive - mod_pagespeed - mod_spdy - WepPageTest, Saturday, 19 October 13 Dulles / Chrome / Cable
- 25. Off the shelf website template http://www.html5xcss3.com/2012/05/html5-template-interio.html Saturday, 19 October 13
- 26. Minimal Optimisations - HTTP 1.1 vs SPDY 0s 1s 2s 3s 4s HTTP SPDY SPDY is faster (GZIP / Keep-Alive / initcwnd 10) Saturday, 19 October 13 5s 6s
- 27. Waterfall for HTTP Test Saturday, 19 October 13
- 28. Waterfall for SPDY Test Saturday, 19 October 13
- 29. So which rules are most likely to be at risk? - Split dominant content domains - Reduce requests - Merging - Sprites - DataURIs Saturday, 19 October 13
- 30. Sharding CSS background: url() images 0s 1s 2s 3s 4s 5s Sharded Not Sharded Sharded page is much slower Saturday, 19 October 13 6s 7s 8s
- 31. Connection to shard opened later New TCP connection opened Saturday, 19 October 13
- 32. New connection shouldn’t have been opened “Both chrome and firefox will automatically unshard transparently for you when using spdy and both of the sharded hosts are at the same IP address and covered under one SSL cert (e.g. *.example.com).” Patrick McManus, Mozilla http://www.stevesouders.com/blog/2013/09/05/domain-sharding-revisited/#comment-60146 Saturday, 19 October 13
- 33. Sharding <img src= 0s 1s 2s 3s 4s 5s 6s Sharded Not Sharded Sharded page is marginally faster??? Saturday, 19 October 13 7s 8s
- 34. Other tests carried out - Sharding JS / CSS Horrible - Merging CSS Slower - Server Push No noticable difference - jQuery from Google CDN Suprisingly quick Saturday, 19 October 13
- 35. It’s only going to get more complex “Situational Performance Optimization, The Next Frontier” Guy Podjarny http://www.flickr.com/photos/freshwater2006/693945631 Saturday, 19 October 13
- 36. Hmm… How do we move forward? http://www.flickr.com/photos/atoach/6014917153 Saturday, 19 October 13
- 37. mod_pagespeed & mod_spdy == tools to experiment # Disable concatenation for SPDY/HTTP 2.0 clients <ModPagespeedIf spdy> ModPagespeedDisableFilters combine_css,combine_javascript </ModPagespeedIf> # Shard assets for HTTP 1.x clients only <ModPagespeedIf !spdy> ModPagespeedShardDomain www.site.com s1.site.com,s2.site.com </ModPagespeedIf> High Performance Browser Networking, Ilya Grigorik Saturday, 19 October 13
- 38. Will complexity lead to the end of hand crafted optimisations? http://www.flickr.com/photos/simeon_barkas/2557059247 Saturday, 19 October 13
- 40. Need to improve our toolkit http://www.flickr.com/photos/alexander/1146677 Saturday, 19 October 13
- 41. Limits to what protocols or automation can fix Requests by Domain Saturday, 19 October 13 Bytes by Domain