Glenn Fleishman has posted some analysis of the impact of RSS aggregators on his blogs' bandwidth use. A well-behaved aggregator should always check to see if the file it's after has been updated before it gets a copy of it, but lots of badly designed aggregators mindlessly pull the same file a couple times an hour (or more), and once you've got ten or a hundred thousand of these pointing at your RSS, going 24/7, it can get awfully expensive. Boing Boing's RSS stats are pretty scary too — check out the log analysis.
I did a quick look at which aggregators represent the most traffic, and a very small number of users employing lwp-trivial, a perl-based HTTP query system, appear to be using over 10 percent of my RSS bandwidth! Time to fix their wagons, to be sure. It makes sense that various Mozilla browsers that have RSS support are using about 15 percent. NetNewsWire makes a very strong showing of 10 percent of usage lately.
(Thanks, Glenn!)
