Wednesday, January 25th, 2006>p>Christopher Merrill over at webperformance.com wrote up an article on the performance impacts of Ajax development in which he measured bandwidth results for an application using full page refreshes vs. Ajax techniques.
In order to test the theory, we decided to see if we could cut the bandwidth use of an application by at least 50%. We selected a rather simple internal data-analysis application. The application consists of a typical page layout with a central section containing the changing content. The header, footer and navigation menu do not change during the application operation. We modified the application so that it can be accessed in either traditional (page-refresh) mode or AJAX mode. We then used our measurement tool (Web Performance Analyzer) to record and analyze the bandwidth utilization of each application.
It is important to note that the application converted in our test was ridiculously simple. Achieving the same bandwidth reduction on a sophisticated application will likely not be as easy, if it is possible at all. However, when applied to extremely large-scale applications or applications with very tight bandwidth considerations, savings of 10% could bring a hefty cost savings.
Performance tests are never blanket statements. In the right place you can utilize Ajax to minimize bandwidth. It is also VERY easy to use Ajax to generate a heck of a lot more bandwidth than required.
Common sense kicks in on when it makes sense to do fine grained calls for data, versus full page refreshes.