High Performance Mobile Web

Patrick Meenan@PatMeenanpmeenan@webpagetest.org

Slides

www.slideshare.net/patrickmeenan

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

DesktopMedian: ~2.7sMean: ~6.9s

Mobile *Median: ~4.8sMean: ~10.2s

* optimistic

How Fast Are Websites Around The World? - Google Analytics Blog

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

"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

LTE HSPA+ 3G

Idle to connected latency < 100 ms < 100 ms < 2.5 s

User-plane one-way latency < 5 ms < 10 ms < 50 ms

● 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 power state transitions (AT&T)

● Idle to Active: 260 ms control-plane latency● Dormant to Active: <50 ms control-plane latency (spec)

https://github.com/attdevsupport/ARO/blob/master/ARODataAnalyzer/src/lte.conf

● 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)

Waterfall Basics

Waterfall Components

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

Total 600-3500 ms 240-500 ms

Network overhead of one HTTP request!

Typical Mobile Network PerformanceCountry Average RTT Average Downlink

ThroughputAverage 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

http://www.belshe.com/2010/05/24/more-bandwidth-doesnt-matter-much/

http://www.belshe.com/2010/05/24/more-bandwidth-doesnt-matter-much/

3G

http://www.belshe.com/2010/05/24/more-bandwidth-doesnt-matter-much/

WiFi/LTE

http://www.belshe.com/2010/05/24/more-bandwidth-doesnt-matter-much/

Smaller resources Fewer resources

The Performance Golden Rule

* http://www.stevesouders.com/blog/2012/02/10/the-performance-golden-rule/

Torbit Insight Real-User Data

http://torbit.com/blog/2012/09/19/some-interesting-performance-statistics/

*WebPagetest performance as measured by New Relic

Front-End: 3.2s* Back-End: 0.010s*

Back-End Front-End

HTTP Archive - Mobile Trends (Feb, 2013)

Content Type Avg # of Requests Avg sizeHTML 6 39 kB

Images 39 490 kB

Javascript 10 142 kB

CSS 3 27 kB

11 Requests, 300KB 784 Requests, 9,200KB

WiFi - Cable (5Mbps, 28ms) 1.5s 28s

3G - Fast (1.6Mbps, 150ms) 2.8s 52s

11 Requests, 300KB 784 Requests, 9,200KB

High Performance Websites

1. Make fewer HTTP requests2. Use CDN3. Add expires header4. Gzip Components5. Put stylesheets at the top6. Put scripts at the bottom7. Avoid CSS expressions8. Make JS and CSS external9. Reduce DNS lookups

10. Minify JS11. Avoid redirects12. Remove duplicate scripts13. Configure Etags14. Make Ajax cacheable15. Sharding domains

basically…..

1 - Deliver smaller resources2 - Send fewer resources

TCP Initial Congestion Window

This:

Is Really:

Linux 2.6.39+ (IW 10):

TCP Initial Congestion Window

Base Page Download TimeUpgraded from Ubuntu 10.04 (2.6.32)to 12.04 (3.2)

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

Browser Prefetcher

External JS Script Resources

Poor Bandwidth Utilization

Browser Prefetcher

External JS Script Resources

Improved Bandwidth Utilization

Watch out for Hidden Images (slideshows in particular)

Main gallery image competing with hidden images and background for bandwidth

http://calendar.perfplanet.com/2013/reducing-domain-sharding/

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.

Sync scripts block the parser...

<script type="text/javascript" src="https://apis.google.com/js/plusone.js"></script>

<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>

Sync script will block the rendering of your page:

Async script will not block the rendering of your page:

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?

Less is more

Parsing JS can take 1ms per KB (uncompressed)

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

brown.edu's mobile home page

125 KB, 1800x800

background image

Break

Measuring Web Performance

Navigation Timing (W3C)

Navigation Timing spec

User’s Connectivity

Server

Front-End

IE 9+ChromeFirefox 9+Android 4+

When is “Done”?(old) Twitter onLoad (1.9s) (old) Twitter end of activity (6.8s)

0 s 7 s 9 s 53 s

http://www.webpagetest.org/video/compare.php?tests=131209_GX_W8Z-r:1-c:0

http://www.webpagetest.org/video/compare.php?tests=131209_GX_W8Z-r:1-c:0

Speed Index: 8592

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

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!

Google Analytics_gaq.push(['_trackTiming', 'UserTimings', 'aft', measuredTime);

Boomerang/Soasta mPulseBOOMR.plugins.RT.setTimer(‘custom0’, measuredTime);

https://gist.github.com/pmeenan/5902672

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/

Custom timings in WebPagetest

Resource Timing

http://www.w3.org/TR/resource-timing/

IE 10+Chrome

Timing for every network-loaded resource

Resource Timing

window.performance.getResourceTimings();

Cross-origin restrictions. Granular timing blanked out unless:

Timing-Allow-Origin: *Timing-Allow-Origin: nullTiming-Allow-Origin: www.example.com

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

Resource from the Network

Resource from Memory Cache

Resource from Disk Cache

https://plus.google.com/u/0/+IlyaGrigorik/posts/EnoiF9PkeYb

Thank You!

Patrick Meenan@PatMeenanpmeenan@webpagetest.org