SPEC WEB99 is a standardized set of benchmarks for measuring performance of Web servers, and it's very interesting to see how the various Web server software and hardware stack up against each other. You can see the results at http://www.specbench.org/osg/web99/results/web99.html. The results show that some of those systems really blast the pages out. You'd have to have pretty heavy traffic to need the fastest systems listed.

Static vs. dynamic pages
Generally speaking, Web servers deliver the strongest performance when they're serving static HTML pages rather than dynamically constructed pages. The reason for this is simple--static HTML pages require no processing power to be expended upon creating the page. The Web server simply needs to get the HTML page from disk or memory and send it back to the client. Dynamically constructed HTML pages, however, require the Web server to carry out a range of tasks to prepare the page prior to returning it to the client. This generally isn't an issue for sites that aren't particularly busy, but once the load on the Web server increases, then all of that dynamic page construction can really begin to tax the Web server, slowing the whole thing down. It's at this point that you need to consider faster servers, more memory, or even implementing multiple servers to share the load. Costs and complexity rapidly go up.

I first noticed just how much load can be placed on a Web server when I was observing the performance of my sitegarden/xml content management system which I have been discussing in recent articles (beginning in the June 2002 issue of DominoPower at http://www.dominopower.com/issues/issue200206/contentmanage001.html). To return a page to a client, a great deal of work had to be performed by not one, but two Web servers running on the same machine. The page content had to be retrieved from Lotus Domino in XML format and grabbed by the Microsoft IIS server. The XML had to be parsed, the relevant data extracted, the page construction logic executed, and finally the HTML buffered and returned to the client.