We are using richfaces 3.2.0 (as 3.2.1GA has a major bug that stops us from using it) and we are experiencing a relatively large memory leak when using the rich:panelMenu component.
If you sit on a page with a panelMenu and refresh a few times you will see that the memory that IE6 is using goes up by about 1MB each time you refresh. This memory is never reclaimed by the OS and the app starts running slower and slower as time goes on.
The leak appears to be the menu as we notice a dramatic change in behavior if we remove it.
This bug was reported and fixed after 3.2.0.. So can't help you while you using old version.