Design with performance in mind
Customers are impatient. You will have to balance the desires of your designers with the needs of your customers. On the one hand there will be a temptation to include the rich media that helps create a compelling site. On the other hand, there is the reality that many of your visitors are viewing your pages over a slower connection than you might use. Before you deploy, try accessing your site using a 56K modem on a machine that is a year or two old. Once you appreciate the time it takes to load your page, you might alter the types of content you include.
After you've actually visited your site, consider whether more sophisticated tools could help identify areas for improvement. IBM WebSphere Page Detailer lets you track everything about a page from the size to the number of items requested to the time needed to request, respond, and deliver these items. The article "Design Pages for Performance" (on the WebSphere Developer Domain High Volume Web Sites zone -- see Resources for a link) provides advice on a range of issues that affect performance and the customer perception of your page.
You should minimize the number, size, and complexity of the items that your page loads. Have fewer than 20 items on a page with the total page size restricted to less than 64K. Take advantage of the browser cache for items that will be used more than once. Items should be requested early so more than one is loading at the same time. You can speed up your site by using persistent connections and avoiding server redirection. Remember that the availability of a site is in the mind of the customer. All of your servers might be up and running, but a slow loading, unresponsive page will just frustrate users.
Even if you can't keep the page size small and the availability high, at least load the high value items first. Think of the times you've wanted a page on a particular Web site but can't remember the direct URL. You go to the site main page and want to quickly navigate to the page you're looking for. If the site loads the menu early, you could select where you want to go before all of the rich media on the page loads. This media is still available for customers who want to see it. Another similar tactic: pages that load with a flash animation and button that visitors can click to skip the introduction. The animation adds value for a new visitor, but is of little interest to a frequent visitor. Previous visitors don't want to wait until the animation is loaded and plays; they just want to get on with their business. The goal, whether you include rich media or not, is to provide a responsive Web page to your customers.