Mobile web performance - MoDev East
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This document summarizes a presentation on high performance mobile web. The presentation covers: - Delivering fast mobile experiences by making fewer HTTP requests, using CDNs, browser prefetching, and other techniques. - Measuring web performance using Navigation Timing, Resource Timing, custom timing marks, and tools like WebPagetest and Google Analytics. - Typical mobile network performance statistics like average latency, download speeds, and how these numbers impact page load times.
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Mobile web performance - MoDev East
- 1. High Performance Mobile Web Patrick Meenan @PatMeenan pmeenan@webpagetest.org
- 3. Schedule 10 - 10:30 - Delivering a fast mobile web experience 10:30 - 11 - Break + Live Website testing/analysis (network Permitting) 11 - 11:20 - Measuring Web Performance 11:20 - 11:30 - Q&A
- 4. Desktop Median: ~2.7s Mean: ~6.9s Mobile * Median: ~4.8s Mean: ~10.2s * optimistic How Fast Are Websites Around The World? - Google Analytics Blog
- 5. Fiber-to-the-home services provided 18 ms round-trip latency on average, while cable-based services averaged 26 ms, and DSL-based services averaged 43 ms. This compares to 2011 figures of 17 ms for fiber, 28 ms for cable and 44 ms for DSL. Measuring Broadband America - July 2012 - FCC
- 6. "Users of the Sprint 4G network can expect to experience average speeds of 3 Mbps to 6 Mbps download and up to 1.5 Mbps upload with an average latency of 150 ms. On the Sprint 3G network, users can expect to experience average speeds of 600 Kbps - 1.4 Mbps download and 350 Kbps - 500 Kbps upload with an average latency of 400 ms." 3G 4G Sprint 400 ms 150 ms AT&T 150 - 400 ms 100 - 200 ms AT&T
- 7. ● ● There is a one time cost for control-plane negotiation User-plane latency is the one-way latency between packet availability in the device and packet at the base station LTE Idle to connected latency User-plane one-way latency HSPA+ 3G < 100 ms < 100 ms < 2.5 s < 5 ms < 10 ms < 50 ms
- 8. LTE power state transitions (AT&T) ● ● ● ● Idle to Active: 260 ms control-plane latency Dormant to Active: <50 ms control-plane latency (spec) Timeout driven state transitions back to idle ○ 100 ms > Dormant ○ 10 s > Idle Similar state machine for 3G devices ○ Except Control Plane latencies are much higher (1-2 seconds) https://github.com/attdevsupport/ARO/blob/master/ARODataAnalyzer/src/lte.conf
- 11. 3G (200 ms RTT) 4G (80 ms RTT) Control plane (200-2500 ms) (50-100 ms) DNS lookup 200 ms 80 ms TCP Connection 200 ms 80 ms TLS handshake (200-400 ms) (80-160 ms) HTTP request 200 ms 80 ms 600-3500 ms 240-500 ms Total Network overhead of one HTTP request!
- 12. Typical Mobile Network Performance Country Average RTT Average Downlink Throughput Average Uplink Throughput South Korea 278 ms 1.8 Mbps 723 Kbps Vietnam 305 ms 1.9 Mbps 543 Kbps US 344 ms 1.6 Mbps 658 Kbps UK 372 ms 1.4 Mbps 782 Kbps Russia 518 ms 1.1 Mbps 439 Kbps India 654 ms 1.2 Mbps 633 Kbps Nigeria 892 ms 541 Kbps 298 Kbps Compare to typical desktop and WiFi performance: < 50 ms RTT, 5 Mbps throughput in the US Source: Ookla/Speedtest.net
- 17. The Performance Golden Rule * http://www.stevesouders.com/blog/2012/02/10/the-performance-golden-rule/
- 18. Torbit Insight Real-User Data http://torbit.com/blog/2012/09/19/some-interesting-performance-statistics/
- 19. Front-End: 3.2s* Back-End: 0.010s* *WebPagetest performance as measured by New Relic
- 21. Content Type Avg # of Requests Avg size HTML 6 39 kB Images 39 490 kB Javascript 10 142 kB CSS 3 27 kB HTTP Archive - Mobile Trends (Feb, 2013)
- 22. 11 Requests, 300KB 784 Requests, 9,200KB
- 23. 11 Requests, 300KB 784 Requests, 9,200KB WiFi - Cable (5Mbps, 28ms) 1.5s 28s 3G - Fast (1.6Mbps, 150ms) 2.8s 52s
- 24. High Performance Websites 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. Make fewer HTTP requests Use CDN Add expires header Gzip Components Put stylesheets at the top Put scripts at the bottom Avoid CSS expressions Make JS and CSS external Reduce DNS lookups Minify JS Avoid redirects Remove duplicate scripts Configure Etags Make Ajax cacheable Sharding domains
- 25. basically….. 1 - Deliver smaller resources 2 - Send fewer resources
- 26. TCP Initial Congestion Window This: Is Really: Linux 2.6.39+ (IW 10):
- 27. TCP Initial Congestion Window Upgraded from Ubuntu 10.04 (2.6.32) to 12.04 (3.2) Base Page Download Time
- 28. WebP ● ● ● ● 40% smaller that jpeg for equivalent quality Supports alpha + lossy New losless support (26% smaller than PNG in testing) Supported by Chrome and Opera
- 29. Browser Prefetcher External JS Script Resources Poor Bandwidth Utilization
- 30. Browser Prefetcher External JS Script Resources Improved Bandwidth Utilization
- 31. Watch out for Hidden Images (slideshows in particular) Main gallery image competing with hidden images and background for bandwidth
- 32. 4 Shards ● ● ● 2 Shards 50-80ms faster page load times for image heavy pages (e.g. search) ○ 30-50ms faster overall. Up to 500ms faster load times on mobile. 0.27% increase in pages per visit. http://calendar.perfplanet.com/2013/reducing-domain-sharding/
- 33. Sync scripts block the parser... Sync script will block the rendering of your page: <script type="text/javascript" src="https://apis.google.com/js/plusone.js"></script> Async script will not block the rendering of your page: <script type="text/javascript"> (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })(); </script>
- 34. Performance rules to keep in mind... (1) JavaScript can block the DOM construction (2) JavaScript can block on CSS (3) Rendering is blocked on CSS... Which means... (1) Get CSS down to the client as fast as you can ○ Unblocks paints, removes potential JS waiting on CSS scenario (2) If you can, use async scripts + avoid doc.write at all costs ○ ○ Faster DOM construction, faster DCL and paint! Do you need scripts in your critical rendering path?
- 35. Less is more Parsing JS can take 1ms per KB (uncompressed)
- 36. Lazy Image Loaders ● Hide images from preloader (good) ● Reduce data use (good) ● Trigger resource loads at arbitrary times (bad) ○ May wake up radio and require 2-3s delay ● Balance bandwidth with experience and battery ○ Maybe load all delayed images after onload
- 37. brown.edu's mobile home page 125 KB, 1800x800 background image
- 39. Break
- 42. Navigation Timing (W3C) IE 9+ Chrome Firefox 9+ Android 4+ Front-End Server User’s Connectivity Navigation Timing spec
- 43. When is “Done”? (old) Twitter onLoad (1.9s) (old) Twitter end of activity (6.8s)
- 46. onload=”performance.mark(‘aft.Image Loaded’)”... window.onload: ● performance.getEntriesByType(“mark”) ● Report latest aft.* as custom time http://blog.patrickmeenan.com/2013/07/measuring-performance-of-user-experience.html
- 47. Roll Your Own ● Send http beacon to beacon server ○ All timings as query params ○ 204 or transparent 1px gif ○ Log requests to access log ● IP, User Agent and Timings all in each record ● access log -> logster -> statsd -> graphite ● Profit!
- 48. Google Analytics _gaq.push(['_trackTiming', 'UserTimings', 'aft', measuredTime);
- 50. AFT vs onload AFT Median 0.932 95th Percentile 4.141 98th Percentile 7.262 onLoad Median 2.235 95th Percentile 11.787 98th Percentile 26.72 http://www.soasta.com/products/mpulse/
- 51. Custom timings in WebPagetest
- 52. Resource Timing IE 10+ Chrome Timing for every network-loaded resource http://www.w3.org/TR/resource-timing/
- 53. Resource Timing window.performance.getResourceTimings(); Cross-origin restrictions. Granular timing blanked out unless: Timing-Allow-Origin: * Timing-Allow-Origin: null Timing-Allow-Origin: www.example.com
- 54. Experiment on webpagetest.org ● Set session cookie to identify new/existing session ● Set browser cookie and local cache value to track cache persistence ● Track performance for sitewide js (site.js) ○ From Cache: responseStart == 0 || responseStart == requestStart
- 56. Resource from the Network
- 57. Resource from Memory Cache
- 58. Resource from Disk Cache