Practical web performance - Site Confidence Web Performance Seminar
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Over of Web performance optimisation (WPO) as well as some results from 25 web performance site analysis. Some information on Mobile web performance as well.
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Practical web performance - Site Confidence Web Performance Seminar
- 1. Practical Web performance Stephen Thair, Seriti Consulting, @TheOpsMgr stephen.thair@seriticonsulting.com 26/09/2011 © Seriti Consulting 1
- 2. Defining “Web Performance”? Why performance matters (to your business) The “Rules” of Web Performance Practical Web Performance (“where to start!”) Agenda 26/09/2011 (c) Seriti Consulting, 2011 2
- 3. My Definition of Web Performance 26/09/2011 (c) Seriti Consulting, 2011 3 “The delay perceived by the website visitor between an action (e.g click) and a meaningful response” “The delay perceived by the website visitor between an action (e.g click) and a meaningful response” “The delay perceived by the website visitor between an action (e.g click) and a meaningful response”
- 4. Perception http://velocityconf.com/velocity2010/public/schedule/detail/13019 26/09/2011 (c) Seriti Consulting, 2011 4
- 5. 26/09/2011 © Seriti Consulting 5 Just because your DevMgr, QA Mgr, Ops Mgr tells you “performance is good” doesn’t means that it is PERCEIVED that way by your CUSTOMERS…
- 6. “Brain wave analysis from the experiment revealed that participants had to concentrate up to 50% more when using badly performing websites, while facial muscle and behavioural analysis of the subjects also revealed greater agitation and stress in these periods. http://www.ca.com/Files/SupportingPieces/final_webstress_survey_report_229296.pdf Poor Performance = Web Stress!!! 26/09/2011 (c) Seriti Consulting, 2011 6
- 7. 0.1 secondsgives the feeling of instantaneous response 1 secondkeeps the user's flow of thought seamless. 10 secondskeeps the user's attention JakobNeilsen. http://www.useit.com/alertbox/response-times.html So what is “Good Performance”? 26/09/2011 (c) Seriti Consulting, 2011 7
- 8. 10 Seconds is too slow… (IMHO) “Initial render” < 750ms and be “Page Complete” < 3 seconds “3 Second Rule” 26/09/2011 (c) Seriti Consulting, 2011 8
- 9. Why Performance Matters 26/09/2011 (c) Seriti Consulting, 2011 9
- 10. Bounce Rate goes up http://www.webperformancetoday.com/2010/06/22/the-90-minute-optimization-life-cycle-faster-by-default-before-our-eyes/ 26/09/2011 (c) Seriti Consulting, 2011 10
- 11. Page Views goes down http://www.webperformancetoday.com/2010/06/22/the-90-minute-optimization-life-cycle-faster-by-default-before-our-eyes/ 26/09/2011 (c) Seriti Consulting, 2011 11
- 12. Conversion Rate goes down http://www.webperformancetoday.com/2010/06/22/the-90-minute-optimization-life-cycle-faster-by-default-before-our-eyes/ 26/09/2011 (c) Seriti Consulting, 2011 12
- 13. “A 1-second delay in page load time equals 11% fewer page views, a 16% decrease in customer satisfaction, and 7% loss in conversions” Aberdeen Group http://www.aberdeen.com/Aberdeen-Library/5136/RA-performance-web-application.aspx 3rd Party Research 26/09/2011 (c) Seriti Consulting, 2011 13
- 14. Artificial 1s delay = 2.8% reduction in revenue per user Empirical Testing 26/09/2011 (c) Seriti Consulting, 2011 14 http://assets.en.oreilly.com/1/event/29/The%20User%20and%20Business%20Impact%20of%20Server%20Delays%2C%20Additional%20Bytes%2C%20and%20HTTP%20Chunking%20in%20Web%20Search%20Presentation.pptx
- 15. You are losing Visitors You are losing Sales You are losing Ad-revenue You are wasting SEO/SEM/PPC budget Spending £££ on bandwidth and servers In Summary… 26/09/2011 (c) Seriti Consulting, 2011 15
- 16. 26/09/2011 © Seriti Consulting 16 So how are we doing?
- 17. 26/09/2011 © Seriti Consulting 17 Largest Page… 4,909,588 bytes
- 18. 26/09/2011 © Seriti Consulting 18 Slowest Page… 12.436 secs
- 19. 26/09/2011 © Seriti Consulting 19 Most objects… 227
- 20. 26/09/2011 © Seriti Consulting 20 1 was down for maintenance 1 didn’t re-direct from http to https ~28% had some type of error
- 21. 26/09/2011 © Seriti Consulting 21 So what can you do about it? Answer = Optimise!
- 22. 26/09/2011 © Seriti Consulting 22 80% “Front End” 20% “Back-end”
- 23. Focus on the “front end” Optimise the interaction between the browser and the data-centre And how the browser processes the client-side objects “Front End Engineering” 26/09/2011 (c) Seriti Consulting, 2011 23
- 25. Use a Content Delivery Network
- 26. Add an Expires or a Cache-Control Header
- 27. Gzip Components
- 28. Put StyleSheets at the Top
- 29. Put Scripts at the Bottom
- 31. Make JavaScript and CSS External
- 33. Minify JavaScript and CSS
- 34. Avoid RedirectsRemove Duplicate Scripts Configure ETags Make AJAX Cacheable Use GET for AJAX Requests Reduce the Number of DOM Elements No 404s Reduce Cookie Size Use Cookie-Free Domains for Components Avoid Filters Do Not Scale Images in HTML Make favicon.ico Small & Cacheable http://developer.yahoo.com/yslow/help/#guidelines 26/09/2011 (c) Seriti Consulting, 2011 24
- 39. Defer loading of JavaScript
- 43. Minify CSS
- 44. Minify HTML
- 47. Minimize DNS lookupsMinimize redirects Optimize images Optimize the order of styles and scripts Parallelize downloads across hostnames Put CSS in the document head Remove unused CSS Serve resources from a consistent URL Serve scaled images Serve static content from a cookieless domain Specify a character set early Specify image dimensions Use efficient CSS selectors http://code.google.com/speed/page-speed/docs/rules_intro.html 26/09/2011 (c) Seriti Consulting, 2011 25
- 48. 26/09/2011 © Seriti Consulting 26 Informationoverload!
- 49. 26/09/2011 © Seriti Consulting 27 Where should you start?
- 50. 26/09/2011 © Seriti Consulting 28 Which optimisations are most common? Which optimisations are most important? And the survey says…
- 51. HTTP Archive - Load Time Correlation 26/09/2011 © Seriti Consulting 29 http://httparchive.org/interesting.php
- 52. HTTP Archive - Render Time Correlation 26/09/2011 © Seriti Consulting 30 http://httparchive.org/interesting.php
- 53. Lessons learnt from consulting… 26/09/2011 © Seriti Consulting 31
- 54. 26/09/2011 © Seriti Consulting 32
- 55. 5 Important Ones Reduce Page Size (<500Kb) Enable (Gzip) Compression Reduce the number of roundtrips (<40 per page…) HTTP Cache Headers (cache long & prosper!) Structure the page (to improve render & download) CSS First Javascript last 26/09/2011 (c) Seriti Consulting, 2011 33
- 56. Even if you apply just those 5 rules…Your page download times will drop by ~50% Low hanging fruit… 26/09/2011 (c) Seriti Consulting, 2011 34
- 57. What about the other rules? Generally you are now measuring gains in milliseconds 26/09/2011 (c) Seriti Consulting, 2011 35 But even milliseconds can make a difference…
- 58. Optimising JavaScript & async loading 26/09/2011 © Seriti Consulting 36 Loading jqueryAsync Improving JS Execution time Delayed ad-loading Faster does not always equal more revenue!!! http://velocityconf.com/velocity2011/public/schedule/detail/18039
- 59. “Reduce the number of DOM elements” 26/09/2011 (c) Seriti Consulting, 2011 37 24,000 calls to a selector takes time…
- 60. “Use a content delivery network” 26/09/2011 © Seriti Consulting 38 You can’t beat the speed of light… And if your customers are not in the UK, invest in a CDN…
- 61. 26/09/2011 © Seriti Consulting 39 4.5 seconds in London becomes 12.5 seconds in Singapore
- 62. “Use http keep-alives” 26/09/2011 © Seriti Consulting 40 Tune your HTTP Keep-Alives! KeepAliveTimeout Value (sec) MaxKeepAlive Requests (# requests/connection) Stop forcing your customers to re-negotiate connections (even partway through a page!) Even more important for SSL! (~4x slower)
- 63. 26/09/2011 © Seriti Consulting 41 “The Bigger Picture”
- 64. 26/09/2011 © Seriti Consulting 42 WPO is not just for Christmas…
- 65. 26/09/2011 © Seriti Consulting 43 Performance is a PROCESS NOT a PROJECT http://www.seriticonsulting.com/blog/2011/5/28/web-performance-is-not-just-for-christmashellip.html
- 66. 26/09/2011 © Seriti Consulting 44 Who should you have on your WPO project team? http://www.seriticonsulting.com/blog/2011/5/29/who-should-be-on-your-wpo-team.html
- 67. 26/09/2011 © Seriti Consulting 45 Who should you have on your WPO Process! team? http://www.seriticonsulting.com/blog/2011/5/29/who-should-be-on-your-wpo-team.html
- 68. 26/09/2011 © Seriti Consulting 46 Performance Lead / Evangelist Front-end Developer Back-end Developer Performance QA Database Administrator Systems Administrator Network Administrator Web Analytics Analyst
- 69. 26/09/2011 © Seriti Consulting 47 Economics of WPO… is automation the answer? http://www.seriticonsulting.com/blog/2011/8/11/why-i-think-automation-is-the-future-of-webperf.html Answer: Maybe?
- 70. 26/09/2011 © Seriti Consulting 48 What Else?
- 71. 26/09/2011 © Seriti Consulting 49 “I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely, in your thoughts, advanced to the stage of Science, whatever the matter may be.” -- William Thomson,1st Baron Kelvin
- 72. 26/09/2011 © Seriti Consulting 50 Make sure you can measure your website performance… (and that the numbers are getting better, not worse!)
- 73. Betfair’s customer performance charter 26/09/2011 © Seriti Consulting 51 ”We aim for 99.9% of bets placed in less than a second and our aspirational website SLA is as follows. Under peak loads, with performance measured at the 95th percentile, for typical user bandwidths and a 0% error rate, our users shall experience Visual Progress (header loaded) in less than 1 second, Time to Interact with useful content within 1.5 seconds and full page loads within 3 seconds. (There is room for improvement on this front as our current sports home page loads in approx. 18 seconds at the 95th percentile). We will publish our aggregate stats here monthly.” http://www.seriticonsulting.com/blog/2011/7/20/creating-an-performance-sla-with-your-customers-betfairrsquo.html
- 74. 10 Seconds is too slow… (IMHO) “Initial render” < 750ms and be “Page Complete” < 3 seconds “3 Second Rule” 26/09/2011 (c) Seriti Consulting, 2011 52
- 75. JavaScript timing e.g. WebTuna, GA SiteSpeed Browser plug-in e.g. HTTPwatch Custom browser e.g. Site Confidence Active Proxy timing e.g. Fiddler proxy Web Server Module e.g. APM solutions Network-level e.g. SC Organic, Atomic Labs Pion 26/09/2011 (c) Seriti Consulting, 2011 53 6 ways of measuring WebPerf
- 76. 26/09/2011 (c) Seriti Consulting, 2011 54 Which is better? It Depends…
- 77. Do you want to measure every visit to your website? Use a jscript tag, web server or network level solution Are you measuring as part of Dev or QA? Use a browser plug-in or proxy Do you want detailed browser metrics like render start time? Use a browser plug-in Are you a 3rd party monitoring provider? Use a custom browser variant! 26/09/2011 (c) Seriti Consulting, 2011 55 It depends on…
- 78. Active Monitoring Agent “pings” the web page “Real-User” Monitoring (RUM) “listening in” to real user traffic Complementary methods! Best solution is Active & Real-User Not Active or Real-User… 26/09/2011 (c) Seriti Consulting, 2011 56 Active vs “Real-User”
- 79. 26/09/2011 © Seriti Consulting 57 What about client-side?
- 80. The Browser performance wars… 26/09/2011 © Seriti Consulting 58 http://sixrevisions.com/infographics/performance-comparison-of-major-web-browsers/ (2009)
- 81. Automate cross-Browser perf testing! 26/09/2011 © Seriti Consulting 59
- 82. 26/09/2011 © Seriti Consulting 60 What about Mobile?
- 83. Different operating systems 26/09/2011 © Seriti Consulting 61
- 84. Even more browsers? 26/09/2011 © Seriti Consulting 62 http://www.webdevelopersnotes.com/articles/mobile-web-browsers-list.php
- 86. 26/09/2011 © Seriti Consulting 64 http://www.nytimes.com/2011/04/18/technology/18mobile.html
- 87. Mobile Performance is location-dependent 26/09/2011 © Seriti Consulting 65 http://mytests.3pmobile.com/context/?WyIyUFVDZHlWV2ErZHFISmxCSWFXRENnPT0iLCJEYnFYVVp3SEN4MD0iXQ%3D%3D
- 88. Mobile latency (over HSDPA) 26/09/2011 © Seriti Consulting 66 Max RTT = 20 seconds! http://blog.davidsingleton.org/mobiletcp
- 89. Mobile performance rules??? Latency kills… DNS Lookups take far longer Avoid re-directs (to http://m.yourdomain.com) Reduce the number of roundtrips (<15 per page?) 26/09/2011 (c) Seriti Consulting, 2011 67
- 90. Mobile performance rules??? “Intelligent Adaptation” Be device & network aware! Send only what you need Send the right sized images With the minimum of script/CSS/etc 26/09/2011 (c) Seriti Consulting, 2011 68
- 91. Mobile performance rules??? Cache Brower cache (small cache, with a different eviction algorithm…) AppCache, LocalStorage, 26/09/2011 (c) Seriti Consulting, 2011 69
- 92. 26/09/2011 © Seriti Consulting 70 And that’s all I’ve got…(but before I go…)
- 93. 26/09/2011 © Seriti Consulting 71 Velocity EU Web Performance Conference Berlin 8th/9th November (see me for a discount code!) http://velocityconf.com/velocityeu/
Notes de l'éditeur
- Very Subjective!!! Perceived… because perception is crucial (as we shall see)Action to Response – from “here to here” – ie any delay experienced has a context of what the customer’s intention is…Meaningful Response – spinners are good, but people won’t wait forever… Different for different sites – for different users (Age, Gender, emotional state (“Is the train about to leave, I’m running late”?), culture, level of experience) – at different stages in the user journey (e.g Navigation browser vs Search vs checkout) Different devices? – Mobile vs wireless vs wired?
- Stoyan’s Talk at Velocity “The Psychology of Performance” http://velocityconf.com/velocity2010/public/schedule/detail/13019"Satisfaction = perception minus expectation" - David Maister
- In fact, your performance could be “stressing them out”….
- This is from the Foviance/ CA Study http://www.foviance.com/what-we-think/its-official-web-stress-is-bad-for-business-2/ http://www.ca.com/Files/SupportingPieces/final_webstress_survey_report_229296.pdf
- The 3 response-time limits are the same today as when I wrote about them in 1993 (based on 40-year-old research by human factors pioneers): 0.1 seconds gives the feeling of instantaneous response — that is, the outcome feels like it was caused by the user, not the computer. This level of responsiveness is essential to support the feeling of direct manipulation (direct manipulation is one of the key GUI techniques to increase user engagement and control — for more about it, see our Principles of Interface Design seminar). 1 second keeps the user's flow of thought seamless. Users can sense a delay, and thus know the computer is generating the outcome, but they still feel in control of the overall experience and that they're moving freely rather than waiting on the computer. This degree of responsiveness is needed for good navigation. 10 seconds keeps the user's attention. From 1–10 seconds, users definitely feel at the mercy of the computer and wish it was faster, but they can handle it. After 10 seconds, they start thinking about other things, making it harder to get their brains back on track once the computer finally does respond.
- As measured @ 2Mbps in IE8…But the actual download speed and browser are irrelevant… this is about user perception… so the real question is “which customers do I want to have a good perception of my site…”
- Can anyone guess why performance matters?
- Front-end – between browser and data centreBack-end – generating the response on the server
- http://code.google.com/speed/page-speed/docs/rules_intro.html
- A review of 25 web performance optimisation engagements performed by Site Confidence over the last 12 months.
- Load time correlation from the HTTP Archive
- Render time correlation from the HTTP Archive
- Based on 25 consulting reports across a wide range of e-commerce and publishing sites
- 100% of the time there were too many requests100% of the time they weren’t using caching to its full advantage, and hence repeat visits were slower than they needed to be…76% of the sites exhibited noticable slowing down during peak time of day/week~50% of the time the pages were bloated (often due to images that on average can be optimised ~15%) Frighteningly ¼ of the sites analysed either didn’t have Gzip compression enabled or it had problems e.g. failing under load!
- The MSN performance talk was excellent http://velocityconf.com/velocity2011/public/schedule/detail/18039Performance improvements can increase and DECREASE your bottom line so be careful!
- In fact this is an example where it took 30 secsIt’s also crappy JavaScript and a poor page design…
- 100ms latency on each request = 5 sec page slowdown on a page100ms is about the latency you would get from here to the US…
- [Next Slide…]But what about “the bigger picture”? Being successful in WPO is more than just “implementing the rules”… so what else can we learn from the experiences of others?
- KeepAliveTimeout DirectiveDescription:Amount of time the server will wait for subsequent requests on a persistent connectionSyntax:KeepAliveTimeout secondsDefault:KeepAliveTimeout 5MaxKeepAliveRequests DirectiveDefault:MaxKeepAliveRequests 100 MaxKeepAliveRequests directive limits the number of requests allowed per connection when KeepAlive is on. If it is set to 0, unlimited requests will be allowed. We recommend that this setting be kept to a high value for maximum server performance.For example:MaxKeepAliveRequests 500
- It’s about measurement…
- WPO Performance isn’t just for Christmas…It’s an on-going effort…
- Just like an ITIL implementation…
- So you need these 8 skills (at a minimum) contributing to your web performance process…But if you are a small startup these all might be one person…Performance Lead / EvangelistFront-end DeveloperBack-end DeveloperPerformance QADatabase AdministratorSystems AdministratorNetwork AdministratorWeb Analytics Analyst
- So a team like that, even part-time, is going to cost you money…… but there are ways to automate it with both commercial (e.g. Aptimize) and open-source (Google’s Mod_pagespeed)What works for you depends on the size and scale of your website, your available resources, etc. OpexvsCapex… Probably a hybrid approach is best – automate where it’s cost-effective, hand-tune the important bits.
- What else? Let’s hear from Lord Kelvin…
- http://www.webperformancematters.com/journal/2007/5/7/the-importance-of-measurements.html
- An dyou can use those measurements as a differentiator in your business!!! – See Betfair’s Performance Charter…This doesn’t have to be esoteric backroom stuff!
- Don’t be afraid to make some noise about it!!! Use it as a BHAG and as a point of differentiation to your competitors!
- Just a reminder…. For those that were paying attention earlier! So how can we measure web performance…
- There are basically 6 techniques used to measure web performance:Each one has it’s pros and cons… easy of use, what it can measure, cost etc
- Operations has different needs to Marketing or User Experience team
- Notethat active monitoring can use either an synthetic agent or a “real browser”Passive – the signal to noise ratio is huge, just like passive sonar. Trying to detect the signal from the clutter is very hard… Anyway, enough about all the WPO projects, what about the
- It’s about measurement…
- This is from 2009 so it’s out of date BUT it makes the point that “which measurement do you choose”http://sixrevisions.com/infographics/performance-comparison-of-major-web-browsers/Aug 2011 data here - http://www.tomshardware.com/reviews/web-browser-performance-standard-html5,3013.html
- It’s about measurement…
- And if you throw in CyanogenMod you can get even better performance…
- Whilst its growing fast… From Souders preso - http://www.slideshare.net/souders/high-performance-mobile-sfsv-web-perf
- From Souders preso - http://www.slideshare.net/souders/high-performance-mobile-sfsv-web-perfObviously this is heavily influenced by sector…e.g. the Adactus guys can tell you about Pizza Hut who do very nicely on mobile!Ditto for music, ringtones etc.
- I was on the Thames Clipper on my way back from the O2 after a concert. So I ran some automated testing and this graphs my results… on the Velocity Conference home page…Min9.275Max156.520Average32.859Median12.071Std Deviation45.691
- Network latency varies enormously…. What can we see here?The connection is relatively good at sending and receiving data. The green crosses represent packets that were actually lost which only happened for 75 of 1000.There are some crazy-high round trip times. The minimum round trip time was 107ms (which would put my home cable connection to shame) and even the median is pretty awesome at 239ms but the maximum was a whopping 20226 ms - that's more than 20 seconds!
- But before I go… two quick plugs…