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Waterfall AntiPatterns - Web Performance Analysis
 

Waterfall AntiPatterns - Web Performance Analysis

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You've been asked to investigate why your web site is loading slowly. You've heard of WebPagetest.org so you enter the URL and run a test. What appears next is a colorful chart that looks like a Dr. ...

You've been asked to investigate why your web site is loading slowly. You've heard of WebPagetest.org so you enter the URL and run a test. What appears next is a colorful chart that looks like a Dr. Seuss illustration. Some bars are long, some are short. Some bars are blue, some are green. "That's nice," you say to yourself, wondering what to do next. It looks benign, innocently simple. But you know it holds many secrets.

The waterfall chart is a mysterious force to some developers. Performance gurus seem to be able to divine the ailments of a slow site at one quick glance. "How?" you wonder. The reality is that anyone can read a waterfall chart - if they know that they are looking for.

This presentation will bestow upon you the ability to recognize specific patterns in a waterfall chart, patterns which are the signs of a slow site. Using these newfound skills, you will become that performance guru and everyone will rejoice.

Presented to the NY Web Performance Group on February 27, 2013.
http://www.meetup.com/Web-Performance-NY/events/101056702/

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    Waterfall AntiPatterns - Web Performance Analysis Waterfall AntiPatterns - Web Performance Analysis Presentation Transcript

    • Waterfall AntiPatterns Rick Viscomi Performance EngineerNY Web Performance Group February 27, 2013
    • About Me● Performance Engineer Scripps Networks Interactive ○ Food Network ○ Travel Channel ○ HGTV● Open source developer ○ trunk8 ○ red dwarf
    • Web Performance
    • Waterfall
    • Waterfall Slope
    • Waterfall AntiPatterns
    • Anatomy of a Request● DNS Lookup● Initial Connection● SSL Negotiation● TTFB● Content Download
    • HTTP Responses● 301 Moved Permanently● 302 Found
    • HTTP Responses ● 304 Not Modified ● Cache static content with long TTL ○ Cache-Control: max-age=31536000 Last-Modified: Wed, 27 Feb 2013 15:17:34 GMT ● Cache busting ○ style_20130228.css
    • HTTP Responses● 404 Not FoundExtra Credit: What happened here?
    • Canceled RequestsInternet Explorer only »
    • Navigation Timing● domContentLoaded* (document.ready)● Start Render (first paint)● loadEvent* (onload)● Document Complete (loadEventStart)* Chrome and Firefox only
    • Navigation Timing
    • Navigation Timing
    • Navigation Timing
    • Request Serialization ● "stair step" pattern ● many requests ● few connections ○ 2-6 ● HTTP 2.0?
    • Request Serialization Connection View cssjavascriptimagesflash
    • Closed Connections ≈● TCP overhead● Enable Keep-Alive
    • Network Silence● bandwidth utilization low● CPU utilization high ○ why?Demo
    • Summary● waterfall slope● request components● HTTP responses ○ redirects ○ conditional GETs ○ errors● page load events● request concurrency● network utilization
    • Thank You Rick Viscomi jrvis.com @rick_viscomiComing Soon: Hands-On Web Performance Optimization Workshop June 18, 2013 Santa Clara, CA
    • Preview: Worst of WebPagetest www.aplia.com ● 46 requests ○ 5 successful ● 21 seconds to Start Render ● 30% gzip savings
    • Preview: Worst of WebPagetest coder143.com ● 443 requests ● 8,000 DOM elements ● 1.6 MB of JavaScript
    • Preview: Worst of WebPagetest www.taboradelaide.edu.au/ ● 2 MB page weight ● 26 second load time ● 17 second repeat view
    • Thank You Rick Viscomi jrvis.com @rick_viscomiComing Soon: Hands-On Web Performance Optimization Workshop June 18, 2013 Santa Clara, CA