At the beginning of the day and on semi-random days, some of my Mac users are experiencing heavy lag. For example, 5-10 minutes to login, several minutes for Safari to load, visible delays while typing in a text field in Safari (e.g. the login form of a certain webapp). This doesn't happen with all users.
The common element appears to be that these users all have their home directories on the same XServe. Users in the same building who have their homedir on either of two other servers do not appear to be effected. All three servers are in the same subnet and all users are in the same subnet. They all have the same Open Directory master. Yet the users on one server have this symptom at the same time that the users of the other two servers do not.