Our perception of response time
Instant Seamless Yawn!100ms 1s 10s 3s - Recommended 7s - Fortune 500 Load Time Average (2010) Response Time in Man-computer Conversational Transactions Robert B. Miller, 1968
80% plus of page load
time is on front-end Backend news.bbc.co.uk Frontend ebay.co.ukdebenhams.co.uk direct.gov.uk amazon.co.uk mumsnet.com guardian.co.uk 0 1.25 2.5 3.75 5 Measured on residential ADSL line using Chrome 19
Get the <head> straight<!doctype html><html><head>
CSS before JS <meta charset="utf-8"> Ideally one ﬁle* <title>This is my title<title> <link rel="stylesheet" href="styles.css" type="text/css" /> <script src="script.js"></script> . . Only JS needed . during page load</head> * Bryan and Stephanie Rieger’s major and minor breakpoint approach requires multiple CSS ﬁles
possible . . . <script src="restofscript.js"></script> </body> </html> One ﬁle or many? (Depends on size) Could you defer some JS until after onload?
Load Third Party scripts asynchronously