Web Performance 101 - Gil Givati

‫נעים להכיר ...‬‫‪ ‬חברה המתמחה במתן שירותים בתחום ניהול ביצועי מערכות‬ ‫בכלל ומערכות מבוססות דפדפן בפרט‬‫‪ ‬מנהלי ‪Israel Web Performance Optimization meetup‬‬ ‫‪ ‬נציגי, מטמיעי ומפתחי פתרונות תוכנה בתחומים:‬ ‫‪ ‬האצת אתרים‬ ‫‪ ‬ניטור ואיתור תקלות בזמן אמת‬ ‫‪www.efficens-software.com ‬‬ ‫‪Twitter: efficens ‬‬ ‫‪ :Facebook ‬אפיסנס סופטוור בע"מ‬ ‫‪http://www.meetup.com/wpo-il ‬‬

‫בתוכנית היום‬ What is Web Performance How does Web Performance affects our bottom line The web Performance building blocks Knowing your audience: understanding Browser behaviors Measuring Performance using YSlow and Google PageSpeed Understanding Waterfalls Working with WebPageTest Working with DynaTrace Ajax Edition JavaScript and you

‫"הזמן הנתפס על ידי המבקר באתר‬ ‫בין פעולה (כמו לחיצה) עד לתגובה‬ ‫משמעותית"‬‫‪Stephan Thair, Seriti consulting‬‬

‫תפיסת הזמן‬http://velocityconf.com/velocity2010/public/schedule/detail/13019

‫איטיות והמוח שלנו‬“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_webstr ess_survey_report_229296.pdf

10 Performanc e 5 improvemen 6 secs 8 secs 2 secs 4 secs t (seconds) 0 -5 -8% -10 -25% -15 -33% Percentage change in -20 -38% page abandonme -25 nt -30 -35 -40urce: Gomez 2010 Study of 500 Million End-User Interactions Across 200+ Web Sites

http://www.webperformancetoday.com/2010/06/22/the-90-minute-optimization-life-cycle-faster-by-default-before-our-eyes/

‫מהם ביצועים טובים ?‬ ‫1.0 שניות נותן תחושה של תגובה מיידית‬ ‫‪‬‬ ‫1 שניה מונע הסחת דעת ומאפשרת רצף מחשבתי‬ ‫‪‬‬ ‫01 שניות שומרות על תשומת לב הגולש‬ ‫‪‬‬ ‫8 שניות הוא הזמן הממוצע שלוקח לגולש לקבל החלטה האם‬ ‫‪‬‬ ‫הוא נשאר בדף או עובר למקום אחר‬‫‪Jakob Neilsen. http://www.useit.com/alertbox/response-times.html‬‬

Web performance anatomy Latency HTTP AJAX/XHR IE FirefoxChrome Browser Internet Server Safari Opera Images CSS JavaScript Cache Flash Parsing DNS 3rd-party Layouting Server servers Rendering

‫מרכיבי זמן התגובה‬ ‫קריטי ליישומי‬ ‫0.2 ‪Web‬‬‫‪Server side‬‬ ‫‪Content delivery‬‬ ‫‪Rendering‬‬ ‫מחוץ למסגרת המערכת אבל‬ ‫עדיין באחריותנו‬ ‫%09-08 מהזמן נצרך מחוץ לגבולות השרת‬ ‫91‬

Bandwidth & Latency

‫הורדת ‪ 200KB‬בקווי‬ ‫‪1.5Mb/Sec‬‬ ‫אורכת כשנייה‬

‫לא הבטיחו לנו ממשק אחיד, פשוט ורזה ?‬

It’s a Multi-Browser World: Different for Each Customer BaseSource: http://arstechnica.com/web/news/2011/02/chrome-takes-10-usage-share-ie-continues-to-haemorrhage.ars; http://gs.statcounter.com/#browser_version-ww-monthly-201001-201101

Load Time Perceived Render 25 20 15Seconds 10 5 0 Source: Gomez Real-User Monitoring Real users around the world 466 million page measurements Broadband connections only 200+ sites

Fragmented, • Who is #1 today? Tomorrow?rapidly-changing 7market • Who is #1 with your customers? 6 8Different • Number of parallel connectionsoperational • JavaScript processingcharacteristics • Etc.  BrowserProcessing • Percentage of totalmoving to the  Networkbrowser response time  Infrastructure • PerformanceMajor impact on • Functionalityuser experience • Appearance

? ‫מה מודדים‬ ‫• בדיקות מבוססות זמן‬ Time to first byte • Time to first impression • onLoad • Fully loaded time •‫• "ציוני תקן" המבוססים על מתודולוגיות ידועות‬ Yahoo! YSlow • Google Page Speed • dynaTrace AJAX edition •

 Minimize HTTP Requests  Remove Duplicate Scripts  Use a Content Delivery Network  Configure ETags  Add an Expires or a Cache-  Make AJAX Cacheable Control Header  Use GET for AJAX Requests  Gzip Components  Reduce the Number of DOM  Put StyleSheets at the Top Elements  Put Scripts at the Bottom  No 404s  Avoid CSS Expressions  Reduce Cookie Size  Make JavaScript and CSS  Use Cookie-Free Domains for External Components  Reduce DNS Lookups  Avoid Filters  Minify JavaScript and CSS  Do Not Scale Images in HTML  Avoid Redirects  Make favicon.ico Small & Cacheablehttp://developer.yahoo.com/yslow/help/#guidelines

 Avoid bad requests  Minimize redirects  Avoid CSS expressions  Optimize images  Combine external CSS  Optimize the order of styles and scripts  Combine external JavaScript  Parallelize downloads across  Defer loading of JavaScript hostnames  Enable compression  Put CSS in the document head  Leverage browser caching  Remove unused CSS  Leverage proxy caching  Serve resources from a consistent  Minify CSS URL  Minify HTML  Serve scaled images  Minify JavaScript  Serve static content from a cookieless domain  Minimize request size  Specify a character set early  Minimize DNS lookups  Specify image dimensionshttp://code.google.com/speed/page-speed/docs/rules_intro.html  Use efficient CSS selectors

? ‫מה חשוב‬http://www.httpArchive.org

‫מהירות טעינה‬ ‫מספר בקשות‬ YSLOW ‫ציון‬ PS ‫ציון‬ ‫שם האתר‬ 2.258 4 94 77 Roninsight 8.042 8 92 88 Roninsight (WP) 4.05 90 74 76 ionroad 22.856 149 70 64 ELAL 13.29 53 73 83 rompr

? ‫רוצים עוד‬ Http KeepAlive • Async JS Load • DOM Elements • CDN •

http://www.efficens-software.com/2011/07/understanding_waterfall_charts/

Webmaster Tools Google Analytics What is measured Time from Initial Page Request to “Document Complete” How it’s measured Google Toolbar Navigation Timing + Google Toolbar on IEBrowsers measured Firefox 2-4 IE 9+ IE 6-9 Chrome 6+ with Google Toolbar & Firefox 7+ PageRank Enabled Android 4+ IE 6-8 with Google Toolbar Sampling rate All Clients (assumed) 1% of clients, max 10K/dayAveraging techniques 7-day running weighted 30-day simple average average (popular pages (average the individual matter more) page’s average load times(

https://developers.google.com/pagespeed/

‫על מה להסתכל ?‬

http://www.gomez.com/instant-test-pro/

What’s the #1cause of slowweb pages?

JAVASCRIPT!

JavaScript performance directlyaffects user experience

The browser UI thread is responsible forboth UI updates and JavaScript execution Only one can happen at a time

<button id="btn" style="font-size: 30px; padding: 0.5em1em">Click Me</button><script type="text/javascript">window.onload = function(){ document.getElementById("btn").onclick = function(){ //do something };};</script>

Before ClickUI Threadtime UI Queue

When ClickedUI Threadtime UI Queue UI Update onclick UI Update

When ClickedUI Thread UI Updatetime UI Queue onclick Draw down state UI Update

When ClickedUI Thread UI Update onclicktime UI Queue UI Update

When ClickedUI Thread UI Update onclick UI Updatetime UI Queue Draw up state

No UI updates whileJavaScript is executing

Loadtime TechniquesDont let JavaScript interfere with page load performance

<!doctype html><html><head> <title>Example</title></head><body> <p>Hello world!</p> <script src="foo.js"></script> <p>See ya!</p></body></html>

ResultUI Thread Hello world! Download Parse Run See ya!time The UI thread needs to wait for the script to download, parse, and run before continuing

Translation:The page doesnt render whileJavaScript is downloading,parsing, or executing duringpage load

ResultUI Thread JavaScript UI Update JavaScript UI Update JavaScripttime The more scripts to download in between UI updates, the longer the page takes to render

Technique #1: Load scriptsdynamically

Basic Techniquevar script = document.createElement("script"), body;script.type = "text/javascript";script.src = "foo.js";body.insertBefore(script, body.firstChild);Dynamically loaded scripts are non-blocking

Downloads no longer blockthe UI thread

Using Dynamic ScriptsUI Thread Hello world! See ya! Run UI Updatetime Download ParseOnly code execution happens on the UI thread, which means less blocking of UI updates

UsageloadScript("foo.js", function(){ alert("Loaded!");});

Timing Note:Script execution beginsimmediately after downloadand parse – timing ofexecution is not guaranteed

Technique #2: Defer scripts

<!doctype html><html><head> <title>Example</title></head><body> <p>Hello world!</p> <script defer src="foo.js"></script> <p>See ya!</p> </body></html>

Support for <script defer>3.5 7.0 5.0 4.0 ?

Deferred scripts begin todownload immediately,but dont execute until all UIupdates complete

Using <script defer>UI Thread Hello world! See ya! More UI More UI Runtime Download Parse Similar to dynamic script nodes, but with a guarantee that execution will happen last

Timing Note: Although scripts always execute after UI updatescomplete, the order of multiple <script defer> scripts is not guaranteed across browsers

Technique #3: Asynchronousscripts

<!doctype html><html><head> <title>Example</title></head><body> <p>Hello world!</p> <script async src="foo.js"></script> <p>See ya!</p> </body></html>

Support for <script async>3.6 7.0 5.0 10 ?

Using <script async>UI Thread Hello world! See ya! Run UI Updatetime Download ParseDownload begins immediately and execution is slotted in at first available spot

Note:Order of execution is explicitly not preserved for asynchronous scripts

Timers

//create a new timer and delay by 500ms setTimeout(function(){ //code to execute here }, 500);setTimeout() schedules a functionto be added to the UI queue aftera delay

Web Workers

Support for Web Workers3.5 4.0 4.0 10 10.6

Web Workers Asynchronous JavaScript execution Execution happens outside the UI thread  Doesn’t block UI updates Data-Driven API  Data is serialized going into and out of the worker  No access to DOM or BOM  Separate execution environment

‫כלים - סיכום‬ Google Page Speed Tools Family http://code.google.com/speed/page-speed/ dynaTrace AJAX Edition http://ajax.dynatrace.com/ajax/en/ Yahoo! YSlow http://developer.yahoo.com/yslow/ WebPagetest http://www.webpagetest.org/ Show Slow http://www.showslow.com/ Lets Make the Web Faster http://code.google.com/intl/en-EN/speed/tools.html

 Books - High Performance Web Sites - Even Faster Web Sites - Website Optimization - Complete Web Monitoring -High Performance JavaScript

gil@efficens-software.com 054-2552060 @efficens

Web Performance 101 - Gil Givati

by Mika Josting on Aug 19, 2012

Accessibility

Categories

Upload Details

Usage Rights

1 Embed 1

Statistics

Web Performance 101 - Gil Givati Presentation Transcript