https://groups.google.com/d/msg/jenkinsci-dev/uAxP7zMc1bc/UGdgzJveqWoJ discusses a performance problem with the essential issue
This was suggested to be a problem in the Git plugin, but recently a similar problem has arisen servicing /view/Main/people/ (loading e.g. http://ci.jenkins-ci.org/people/ can be used as a live example):
The common issue is that People.getUserInfo is traversing every build of every job in the system, which on its own can be a heavyweight operation in a large installation, and then triggering changelog.xml parses for each such job (the result is held weakly so will often be missing).
While it can certainly be useful to display build-derived information about people in the system, this should be considered optional information, and must be provided asynchronously if at all so that page load does not block on it and it can be easily canceled (e.g. by moving to another page).