Figure 17-17. http://www.msn.com
The MSN home page (http://www.msn.com), ranks in the middle among the sites examined in this chapter when it comes to total size and number of HTTP requests. It fails to meet some basic performance guidelines, due especially to the way ads are inserted. However, it has several positive performance traits not seen in any of the other web sites analyzed here. Let's start by looking at how MSN does ads, because this will come up in several of the following recommendations.
MSN uses IFrames to insert five ads into the page. As discussed
earlier, with regard to eBay, using IFrames is an easy way to remove
dependencies between the ads system and the HTML page generation system.
However, each IFrame results in an additional HTTP request. In the case
of MSN, each IFrame's
is set to
about:blank, which doesn't
generate any HTTP traffic. However, each IFrame contains an external
document.write. Integrating the ad system and
the HTML page generation system would preclude the need for these five
HTTP requests. Instead of requesting a script that contains multiple
document.write statements, that
The MSN home page has four scripts (other than the scripts used for ads), three of which are loaded very close together ...