Last week, CyberNet Technology News published a useful article called Reducing Your Memory Usage In Firefox that lists a number of Firefox extensions that apparently leak memory. The article includes links to Bugzilla reports for many of the memory leaks in question, which may make some people more confident about the validity of these claims.
It will be interesting to see how quickly the Firefox community is able to respond and address some of these memory leaks and performance problems that affect some of the most popular extensions.
See also: Download.com Publishes Handy Firefox Optimization Tips