Btw,
I am not sure you could say the XWiki installs are that "pesky".
However, depending on the user base, it may really need quite some tuning.
For example, if your xwiki manipulates complex documents the document cache may be too big
for the memory, and that you only reach with some time (it could be a week or two).
OutOfMemoryErrors then appear on a regular basis.
Another example has been the amount of registered users. This is a bit too much on curriki
to store into a page of objects, so special treatment has been applied.
Yet another example would be the mass of attachments, e.g if people use this as a shared
disk, where the file-system-attachments solution has helped quite many (I think).
I think all wikis and CMSs that I know of are rather limited in their default goals
(beyond XWiki, I have experience with Drupal and Wordpress) and special treatment maybe be
quickly available, in config, install, or custom development.
Monitoring tools can help you adjust this.
Bryn, maybe you want to indicate how big is your system?
Maybe it's just a matter of some too eager clients (e.g. some ever repeat
javascript-based-requests served to tens of users every second or so)?
paul