Graphics and network bandwidth
Many Web users currently access their Internet service providers via 56 kilobits per second (KBps) modems from their homes, offices, or remote work sites. At 56 KBps the actual download rate is only about 7 kilobytes (KB) per second (8 bits make a byte). This means that a modest 36 KB graphic on your Web page could take five seconds or longer to load into the reader's Web browser. Actual data transmission rates will vary depending on the user's modem, Web server speed, Internet connection, and other factors, but the overall point is clear: the more graphics you incorporate, the longer the reader will have to wait to see your page. A full-screen graphic menu on your home page plus background graphics could leave your modem-based readers twiddling their thumbs for a full minute or more, even if they have a state-of-the-art modem and a good Internet connection. Look at your watch (better yet, hold your breath) for a full minute, then decide whether you're willing to ask your users to wait this long when they visit your Web site.
A better strategy is to increase the graphics loading of your pages gradually, drawing users into your site with reasonable download times. As readers become more engaged with your content, they will be more willing to endure longer delays, especially if you give them notes about the size of graphics or warnings that particular pages are full of graphics and will take longer to download. At today's average modem speeds most pages designed for users dialing in from home should contain no more than 50 to 75 kilobytes of graphics.
Graphics and intranets
Luckily for graphic designers, many Web sites are created primarily for educational, organizational, and commercial users who access their local intranets and the larger World Wide Web from the school or office at Ethernet speeds or greater. Also, increasing numbers of home users now have access to higher-speed connections like DSL and cable modems. Graphics and page performance are also an issue for these users, but it makes little sense to restrict Web page graphics arbitrarily in the cause of "saving network bandwidth." The bandwidth gearheads always miss the point: graphics are what drew most people to the Web in the first place. If you've got the access speed, indulge!