I am working with a customer who is having Outlook/Exchange performance issues. Specifically, when they try to book conference rooms (selecting multiple conference room calendars and viewing free/busy to check availability), it hangs their Outlook client up sometimes several seconds, even minutes. Other users reported slowness at times when just composing a message as well (hangs for a few seconds). This is an exchange 2003 organization, one administrative group with 6 local servers (one of them is a dedicated public folder server) and 3600 users. In reviewing Exchange Best Practices Analyzer reports, there is nothing major. I did notice that there was an informational item indicating that there was just a single replica of the free/busy folder. I have been reading conflicting information as to whether there should be multiple replicas within an adminstrative group. Here is the link from the EXBPA report ( http://technet.microsoft.com/en-us/library/aa997382.aspx
Other documentation from MS I have found indicates that you should not have multiple replicas unless others are in a different physical location and with a slow link. In this case, all servers are local and users on on the LAN (although there are some remote users who VPN in).
Should I create another replica on a server within a site? I would be concerned then about replication lag, but if it will increase performance I would recommend it. Also, the "show free/busy" details is the default setting for all the OUtlook users.