MSDN Magazine - November 2008 - (Page 72)

U t i l i t y S p ot l i g h t 12 Steps To Faster Web Pages With Visual Round Trip Analyzer Jim pierson So many factors can affect the performance of a Web page— analysis using VRTA. But before we begin, find out how much you the distance between server and client, the size of the elements on the page, how the browser loads these elements, available bandwidth. Finding those bottlenecks and identifying the culprits is no easy task. But identifying the causes can yield some significant improvements. In this article, I’ll show you how to spot and remedy some common causes of poor performance. I’ll also introduce you to Visual Round Trip Analyzer (VRTA), a tool that can distinguish among the various factors that cause performance problems and present them as a graphical map. Then I’ll show you how to perform your this article is based on a prerelease version of VRtA. All information is subject to change. already know by taking the speed quiz called “How Do You Improve Page Loading?” that is included in this article. Location, Location, Location this article discusses: • Anatomy of a round-trip • tips for faster Web pages • Visual Round trip Analyzer technologies discussed: Visual Round trip Analyzer Code download available at: msdn.microsoft.com/magazine/cc135911 72 msdn magazine Two of the biggest factors in page load delays are distance, measured as round-trip time (RTT), and the number of round-trips between the client and servers. A round-trip is a network packet sent by a client to a server, which then sends a response packet. Downloading a single Web page can require as few as 2 or 3 round-trips if the page is sparse, or many tens of round-trips for a rich appearance. Opening a TCP connection is one round-trip. Sending a Get and receiving the first 3KB is one round-trip. Sending Acknowledgements for more data is more round-trips. For users who are located near the Web site data center, say less than several hundred miles away such as a user in Los Angeles connecting to a server in Silicon Valley, RTT is only 20ms (.020 seconds) and not a significant factor in page load time. There could be 50 round-trips back and forth between the client and server in these circumstances and the page-load time would still only have 1 second of network delay before any server time was added (50 RTs × 20ms = 1 sec). But the story is much different for a user in Europe or Asia connecting to the same Silicon Valley server. Japan and England are currently 120ms in round-trip time from California at minimum. http://msdn.microsoft.com/magazine/cc135911

Table of Contents Feed for the Digital Edition of MSDN Magazine - November 2008

Contents MSDN Magazine - November 2008 Toolbox CLR Inside Out Data Points Cutting Edge Security Briefs Test Your Security IQ Agile SDL Access Control Utility Spotlight RIA Test Run Wicked Code Foundations Team System End Bracket

MSDN Magazine - November 2008

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