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
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!
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.
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…
Practical web performance - Site Confidence Web Performance Seminar
Defining “Web Performance”?<br />Why performance matters (to your business)<br />The “Rules” of Web Performance<br />Practical Web Performance (“where to start!”)<br />Agenda<br />26/09/2011<br />(c) Seriti Consulting, 2011<br />2<br />
My Definition of Web Performance<br />26/09/2011<br />(c) Seriti Consulting, 2011<br />3<br />“The delay perceived by the website visitor between an action (e.g click) and a meaningful response”<br />“The delay perceived by the website visitor between an action (e.g click) and a meaningful response”<br />“The delay perceived by the website visitor between an action (e.g click) and a meaningful response”<br />
“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.<br />http://www.ca.com/Files/SupportingPieces/final_webstress_survey_report_229296.pdf<br />Poor Performance = Web Stress!!!<br />26/09/2011<br />(c) Seriti Consulting, 2011<br />6<br />
0.1 secondsgives the feeling of instantaneous response <br />1 secondkeeps the user's flow of thought seamless. <br />10 secondskeeps the user's attention<br />JakobNeilsen. http://www.useit.com/alertbox/response-times.html<br />So what is “Good Performance”?<br />26/09/2011<br />(c) Seriti Consulting, 2011<br />7<br />
10 Seconds is too slow… (IMHO)<br />“Initial render” < 750ms and be <br />“Page Complete” < 3 seconds <br />“3 Second Rule”<br />26/09/2011<br />(c) Seriti Consulting, 2011<br />8<br />
“A 1-second delay in page load time equals 11% fewer page views, a 16% decrease in customer satisfaction, and 7% loss in conversions” <br />Aberdeen Group<br />http://www.aberdeen.com/Aberdeen-Library/5136/RA-performance-web-application.aspx<br />3rd Party Research<br />26/09/2011<br />(c) Seriti Consulting, 2011<br />13<br />
You are losing Visitors<br />You are losing Sales<br />You are losing Ad-revenue<br />You are wasting SEO/SEM/PPC budget<br />Spending £££ on bandwidth and servers<br />In Summary…<br />26/09/2011<br />(c) Seriti Consulting, 2011<br />15<br />
Focus on the “front end”<br />Optimise the interaction between the browser and the data-centre<br />And how the browser processes the client-side objects<br />“Front End Engineering”<br />26/09/2011<br />(c) Seriti Consulting, 2011<br />23<br />
Minimize DNS lookups</li></ul>Minimize redirects<br />Optimize images<br />Optimize the order of styles and scripts<br />Parallelize downloads across hostnames<br />Put CSS in the document head<br />Remove unused CSS<br />Serve resources from a consistent URL<br />Serve scaled images<br />Serve static content from a cookieless domain<br />Specify a character set early<br />Specify image dimensions<br />Use efficient CSS selectors <br />http://code.google.com/speed/page-speed/docs/rules_intro.html<br />26/09/2011<br />(c) Seriti Consulting, 2011<br />25<br />
Even if you apply just those 5 rules…Your page download times will drop by ~50%<br />Low hanging fruit…<br />26/09/2011<br />(c) Seriti Consulting, 2011<br />34<br />
What about the other rules?<br />Generally you are now measuring gains in milliseconds<br />26/09/2011<br />(c) Seriti Consulting, 2011<br />35<br />But even milliseconds can make a difference…<br />
10 Seconds is too slow… (IMHO)<br />“Initial render” < 750ms and be <br />“Page Complete” < 3 seconds <br />“3 Second Rule”<br />26/09/2011<br />(c) Seriti Consulting, 2011<br />52<br />
Do you want to measure every visit to your website?<br />Use a jscript tag, web server or network level solution<br />Are you measuring as part of Dev or QA?<br />Use a browser plug-in or proxy<br />Do you want detailed browser metrics like render start time?<br />Use a browser plug-in<br />Are you a 3rd party monitoring provider?<br />Use a custom browser variant! <br />26/09/2011<br />(c) Seriti Consulting, 2011<br />55<br />It depends on…<br />
Active Monitoring<br />Agent “pings” the web page<br />“Real-User” Monitoring (RUM)<br />“listening in” to real user traffic<br />Complementary methods!<br />Best solution is Active & Real-User<br />Not Active or Real-User…<br />26/09/2011<br />(c) Seriti Consulting, 2011<br />56<br />Active vs “Real-User”<br />
Mobile performance rules???<br />Latency kills… <br />DNS Lookups take far longer<br />Avoid re-directs (to http://m.yourdomain.com)<br />Reduce the number of roundtrips (<15 per page?)<br />26/09/2011<br />(c) Seriti Consulting, 2011<br />67<br />
Mobile performance rules???<br />“Intelligent Adaptation”<br />Be device & network aware!<br />Send only what you need<br />Send the right sized images<br />With the minimum of script/CSS/etc<br />26/09/2011<br />(c) Seriti Consulting, 2011<br />68<br />
Mobile performance rules???<br />Cache<br />Brower cache (small cache, with a different eviction algorithm…)<br />AppCache, <br />LocalStorage, <br />26/09/2011<br />(c) Seriti Consulting, 2011<br />69<br />