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Steve Souders Even Faster Websites Disclaimer: This content does not necessarily reflect.

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Presentation on theme: "Steve Souders Even Faster Websites Disclaimer: This content does not necessarily reflect."— Presentation transcript:

1 Steve Souders souders@google.com http://stevesouders.com/docs/cbs-20090209.ppt Even Faster Websites Disclaimer: This content does not necessarily reflect the opinions of my employer.

2 17% 83% iGoogle, primed cache The Importance of Frontend Performance 9%91% iGoogle, empty cache

3 Time Spent on the Frontend Empty CachePrimed Cache www.aol.com97% www.ebay.com95%81% www.facebook.com95%81% www.google.com/search47%0% search.live.com/results67%0% www.msn.com98%94% www.myspace.com98% en.wikipedia.org/wiki94%91% www.yahoo.com97%96% www.youtube.com98%97% April 2008

4 The Performance Golden Rule 80-90% of the end-user response time is spent on the frontend. Start there. greater potential for improvement simpler proven to work

5 14 Rules 1.Make fewer HTTP requests 2.Use a CDN 3.Add an Expires header 4.Gzip components 5.Put stylesheets at the top 6.Put scripts at the bottom 7.Avoid CSS expressions 8.Make JS and CSS external 9.Reduce DNS lookups 10.Minify JS 11.Avoid redirects 12.Remove duplicate scripts 13.Configure ETags 14.Make AJAX cacheable

6 High Performance Web Sites YSlow

7 http://en.oreilly.com/velocity2009 June 22-24, 2009

8

9 Even Faster Websites 1.Split the initial payload 2.Load scripts without blocking 3.Don't scatter inline scripts 4.Couple asynchronous scripts 5.Split dominant domains 6.Simplify CSS Selectors 7.Use iframes sparingly 8.Flush the document early O'Reilly, Q2 2009

10 AOL eBay Facebook MySpace Wikipedia Yahoo! Why focus on JavaScript? YouTube

11 Scripts Block blocks parallel downloads and rendering What's "Cuzillion"? http://stevesouders.com/cuzillion/?ex=10008

12 a tool for quickly constructing web pages to see how components interact Open Source http://stevesouders.com/cuzillion/ Cuzillion 'cuz there are a zillion pages to check

13 JavaScript Functions Executed before onload www.aol.com115K30% www.ebay.com183K44% www.facebook.com1088K 9% www.google.com/search15K45% search.live.com/results17K24% www.msn.com131K31% www.myspace.com297K18% en.wikipedia.org/wiki114K32% www.yahoo.com321K13% www.youtube.com240K18% 26% avg 252K avg Initial Payload and Execution

14 Split the initial payload split your JavaScript between what's needed to render the page and everything else load "everything else" after the page is rendered separate manually (Firebug); tools needed to automate this (Doloto from Microsoft) load scripts without blocking – how?

15 MSN Scripts and other resources downloaded in parallel! How? Secret sauce?! var p= g.getElementsByTagName("HEAD")[0]; var c=g.createElement("script"); c.type="text/javascript"; c.onreadystatechange=n; c.onerror=c.onload=k; c.src=e; p.appendChild(c) MSN.com: Parallel Scripts

16 Advanced Script Loading XHR Eval XHR Injection Script in Iframe Script DOM Element Script Defer document.write Script Tag

17 XHR Eval script must have same domain as main page must refactor script var xhrObj = getXHRObject(); xhrObj.onreadystatechange = function() { if ( xhrObj.readyState != 4 ) return; eval(xhrObj.responseText); }; xhrObj.open('GET', 'A.js', true); xhrObj.send(''); http://stevesouders.com/cuzillion/?ex=10009

18 XHR Injection var xhrObj = getXHRObject(); xhrObj.onreadystatechange = function() { if ( xhrObj.readyState != 4 ) return; var se=document.createElement('script'); document.getElementsByTagName('head') [0].appendChild(se); se.text = xhrObj.responseText; }; xhrObj.open('GET', 'A.js', true); xhrObj.send(''); script must have same domain as main page http://stevesouders.com/cuzillion/?ex=10015

19 Script in Iframe

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