There are a lot of ways to improve performance in web applications. One of the simplest but most effective methods is to cache images on the client. In this article I would like to show how we implemented image caching for our website.
When she was building the website http://www.software-architects.com she used a lot of images in the css style sheets to display background images for menu items. After transfering the files to our web server she tested how much traffic a request to our start page would produce with Microsoft Network Monitor. This is a Tool to allow capturing and protocol analysis of network traffic. You can download it from the Microsoft Download Center.
With Microsoft Network Monitor 3.1 she recorded a call to http://www.software-architects.com. As a result she got 20 requests to 20 different files to display one single page. Microsoft Network Monitor shows that appoximatly half of the requests are required for the menu images.
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