I have worked a bit with the segment editor. It is easy to configure segments with a lot of wildcard like searches which may bring the server into trouble. In General, the function is very helpful, but from my perspective it should be great to have an option to offer creation and editing of segments to certain users or only administrators.
I have defined 10 different segments and a background archive.php-process every hour. The result was, that the archive processes of 9 am were not finished until 10 am when the next archive processes were starting and of course, at 11 am the same. After some further hours, the server had a load of 18… I would recommend, that a process may check whether the same process is running on the machine before it will start again.